In my latest campaign the party is dealing with a Necromancer in the Shadowfell that acts as a surgeon for the undead. I've been using the optional Lingering Injuries rules in this campaign, so one character has lost a hand and another has lost an eye so I decided to resurrect the Undead Graft rules from Libris Mortis with a 5e makeover and offer them to the players as options. Here are some of what I've come up with. I took a stab at pricing these grafts similar to magic items. I didn't want them to require attunement, so I've been adding detrimental properties largely drawn and inspired from the tables used for Artifacts in the DMG. It seems reasonable that grafting the undead to your body should have some negative consequences.

ARM GRAFTS

Skeletal Arm (50 gp)

• Your unarmed attacks with this arm deal 1d6 + STR/DEX slashing damage.
• You have Vulnerability to Bludgeoning damage. If the source of the Bludgeoning damage is an attack roll, roll 1d6. If the d6 rolls 3 or higher you do not have Vulnerability to Bludgeoning for this attack.

Zombie Arm (100 gp)

• Your unarmed attacks with this arm deal 1d8 + STR bludgeoning damage.
• Beasts within 30 feet of you that have a Challenge Rating of 6 or lower are Hostile toward you.

Ghostly Arm (1,000 gp)

• You can cast Chill Touch (using CHA, INT, or WIS)
• Incorporeal. As a Magic Action you can move this arm and anything it is carrying to or from the Border Ethereal. This arm is visible on the Material Plane while on the Border Ethereal and vice versa, but it can’t affect or be affected by anything on the other plane.
• Sentient Item. A vestige of the ghost's personality remains and it retains some sentience. Treat the arm as a sentient magic item that communicates by emotions. When creating this item, roll 1d10 on the Sentient Item's Special Purpose table for it's Special Purpose. Additionally, roll 2d6 + 7 to set the Charisma DC for when the personality is in conflict.

Shadow Arm (600 gp)

• 3/day you can cast Ray of Enfeeblement (DC 13) as a Magic Action but as a Melee Spell Attack with a range of 5 ft.
• Amorphous. The shadowy arm can move through a space as narrow as 1 inch.
• Nonmagical flames are extinguished within 30 feet of you.

Ghoul Arm (500 gp)

• Your unarmed attacks with this arm may deal 1d4 + STR Slashing damage and if you hit a creature that isn’t an Undead or elf, that creature is subjected to the following effect. Constitution Saving Throw: DC 10. Failure: The target has the Paralyzed condition until the end of its next turn.
• You emit a sour stench noticeable from up to 10 feet away. You have Disadvantage on all Charisma checks with creatures in this radius.

Flaming Skeleton Arm (2,000 gp)

• You can cast Produce Flame (using CHA, INT, or WIS)
• * While Produce Flame is active, any weapon you are holding in this hand is wreathed in magical flames and any melee or unarmed attack made with it deals an extra 1d6 fire damage on a hit.
• You have Vulnerability to Bludgeoning damage. If the source of the Bludgeoning damage is an attack roll, roll 1d6. If the d6 rolls 3 or higher you do not have Vulnerability to Bludgeoning for this attack.

Greater Zombie Arm (3,000 gp)

• Your unarmed attacks with this arm deal 2d6 + STR bludgeoning damage.
• Your Strength score increases by 2, to a maximum of 20
• Your Dexterity score is reduced by 2, to a minimum of 3.

Mummified Arm (3,250 gp)

• 3/day a creature hit by your unarmed attack is cursed. While cursed, the target can’t regain Hit Points, its Hit Point maximum doesn’t return to normal when finishing a Long Rest, and its Hit Point maximum decreases by 10 (3d6) every 24 hours that elapse. A creature dies and turns to dust if reduced to 0 Hit Points by this attack.
• You have Vulnerability to Fire damage. If the source of the Fire damage is an attack roll, roll 1d6. If the d6 rolls 3 or higher you do not have Vulnerability to Fire for this attack.

Ghast Arm (4,000 gp)

• Your unarmed attacks with this arm deal 2d6 + STR Slashing damage and if the target is a creature that isn’t an Undead or elf, it is subjected to the following effect. The target has the Paralyzed condition until the end of its next turn.
• You emit a foul stench and other creatures can’t take Short or Long Rests while within 300 feet of you.

Wight Arm (4,000 gp)

• Your shadow-wreathed hand can siphon life force from others to heal your wounds. 2/day you may cast *Vampiric Touch*.
• You kill any nonmagical vegetation within 10 feet of you that isn’t a creature.

Lich Arm (6,000 gp)

• Any melee spell attack you make with the arm and any melee attack made with a weapon held by it deals an extra 2d6 Cold damage on a hit.
• Sentient Item. A vestige of the lich's personality remains and it retains some sentience. Treat the arm as a sentient magic item that communicates by emotions. When creating this item, roll 1d10 on the Sentient Item's Special Purpose table for it's Special Purpose. Additionally, roll 2d4 + 12 to set the Charisma DC for when the personality is in conflict.

EYE GRAFTS

Zombie Eye (100 gp)

• You have Darkvison out to 60 ft.
• Your Wisdom is reduced by 2 to a minimum of 3.

Ghostly Eye (3,000 gp)

• You gain Darkvision out to 60 ft.
• Ethereal Sight. You can see 60 feet into the Ethereal Plane when you are on the Material Plane.
• Sentient Item. A vestige of the ghost's personality remains and it retains some sentience. Treat the eye as a sentient magic item that communicates by emotions. When creating this item, roll 1d10 on the Sentient Item's Special Purpose table for it's Special Purpose. Additionally, roll 2d6 + 7 to set the Charisma DC for when the personality is in conflict.

Bodak's Eye, (6,000 gp)

• You gain Darkvision out to 120 ft.
• Withering Gaze. One creature that you can see within 60 feet of you must make a DC 13 Constitution saving throw, taking 22 (4d10) necrotic damage on a failed save, or half as much damage on a successful one.
• Sunlight Sensitivity. While in sunlight, you have disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Mummified Eye, (8,000 gp)

• You gain Darkvision out to 60 ft.
• Dreadful Glare. 2/day you may cast Eyebite (save DC 17, "Panicked" only)
• Erases scrolls within 10 feet of itself, rendering them nonmagical.

Eye of Flame, (10,000 gp)

• You gain Darkvision out to 60 ft.
• Hellfire Orb. 1/day upon command. DC 17, each creature in a 20-foot-radius Sphere centered on a point you can see within 120 feet. Failure: 5d6 Fire damage plus 5d6 Necrotic damage. Success: half damage.
• Dilutes potions within 10 feet of itself, rendering them nonmagical.

Man, this is sick! What about some leg grafts?

In the 3.5e Libris Mortis book they didn't have any leg grafts. Probably because most of the undead move about the same speed, so there wouldn't be any improvement. You'd probably need to swap out both as well. I could see the tireless nature of the undead letting you do long marches without gaining Exhaustion. 

I did find a few I haven't posted here. Mohrg's Tongue, Vampire Fangs, and Undead Skin. 

One of my players is a lizardfolk and is curious about enhancements to their bite, so I drafted up a Vampire Fang graft conversion from the original. Since an Enspelled Dagger could cast Vampiric Touch 6 times, you could probably have it up in almost every fight, this constant use but with restrictions is probably fine priced at the high end of Rare. I was looking for a Major Detrimental Property and just keeping one of the Vampire's weaknesses seemed perfect.

Vampiric Fangs, (5,000 gp)

• Your fanged bite can be used to make an unarmed attack that targets one willing creature, or a creature that is grappled by you, incapacitated, or restrained. This bite deals 1d4 + CON piercing damage plus 3d6 necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and you regain hit points equal to half that amount. The reduction lasts until the target finishes a long rest.
• Forbiddance. You can’t enter a residence without an invitation from one of the occupants.

There might also be a negligible chance of catching vampirism. 

Quote from CrowKeeper >>

One of my players is a lizardfolk and is curious about enhancements to their bite, so I drafted up a Vampire Fang graft conversion from the original. Since an Enspelled Dagger could cast Vampiric Touch 6 times, you could probably have it up in almost every fight, this constant use but with restrictions is probably fine priced at the high end of Rare. I was looking for a Major Detrimental Property and just keeping one of the Vampire's weaknesses seemed perfect.

Vampiric Fangs, (5,000 gp)

• Your fanged bite can be used to make an unarmed attack that targets one willing creature, or a creature that is grappled by you, incapacitated, or restrained. This bite deals 1d4 + CON piercing damage plus 3d6 necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and you regain hit points equal to half that amount. The reduction lasts until the target finishes a long rest.
• Forbiddance. You can’t enter a residence without an invitation from one of the occupants.

There might also be a negligible chance of catching vampirism. 

 

 Neat.