Originally Posted by RedBMaster

So as for XRAY parts many many parts will bolt straight on! Please note many XRAY parts haven't been changed since the T2/3, but in general most T4 parts will fit. I have not seen a list of compatible parts, but I may as well start one.

Compatible Parts:
XRAY:
- rear gear diff (note: loosen bottom bulkhead screws as it's a tad wider than the stock diff. Stock gears do not work in XRAY diff, but lightened steel outdrives will leak a bit. However the aluminum BT-4 outdrives work perfect)
- C hub (4° is kit)
- front arms (1 hole is kit and 2 hole work as well)
- rear arms
- steering blocks (Hard is kit)
- spool outdrives
- belts front and rear
- sway bar front and rear
- sway bar holder (303411)
- 4.9mm ball cups
- rear hubs
- foam front bumpers
- front bumper plate, but requires XRAY front body mounts
- rear body posts
- T4 2015 FF, FR, and RR arm/suspension mounts
- T3/T4 Springs (4s springs don't fit, but the older ones do)
- T4 2014 Front and rear bulkheads

3Racing:
- C hub and steering blocks (should be used together)
- front sway bar (only the bar tho)
- rear hubs

Spec-R:
- steering blocks
- C hub
- gear diff for the XRAY (not verified)
- front sway bar (at least the bar, haven't tried the rest)
- spool outdrives
- rear body posts
- front body posts require XRAY bumper plate

VBC:
- rear diff

Spur Gears:
- 3Racing
- Robinson Racing
- Serpent *preferred and lightest
- XRAY (can only use 2 screws and must shim the axle to remove slop)

Servo Savers:
- Kimbrough med
- XRAY xstiff
- Tamiya xstiff
- yokomo bmax2's saver
***Note: You have to move the servo all the way up in the stock mount and use a super short screw in the metal bracket to attach it to the chassis. I couldn't find one so I ground one down with a Dermal. ***


NOT WORKING:
XRAY:
- T4 2015 RF single or two piece arm mount
- Spur/Motor Mount

Durango:
- steel front spool outdrives

3Racing:
- rear sway bars
- sway bar linkage
- rear gear diff
- arm mounts

Spec-R:
- floating servo mount
- ball cups
- rear hubs (axle hole too small)
- front spool

Basher BT-4:
- lightened steel gear diff outdrives (caused diff to leak)
- springs (require shorter shocks which require shorter towers)


Last updated: 9/01/2016
PM me with any additional updates