The tranny thats in my car now is leaking everywhere and so is the motor, lol. Im getting ready to do a round of repairs (oil pan gasket, front & rear main seals, cam seal, timing belt, tensioner, water pump, thermostat, clutch, flywheel & axles)

Ive had this short ratio d-series tranny Ive been trying to build since like 2 years ago, lol. Ive had all the parts to do it, but just havent found the time yet. So since Im going to have everything apart for all the other stuff, I figure its a good time to go ahead and swap in the new tranny too.

The last time was messing with the tranny, I stopped at the point of shimming the OBX because I didn't have the right size shim. I finally ordered a shim a couple weeks ago and today I got that done and started to put the rest of it together but I got hung up on something..

I tried to "bench shift" into all the gears just to make sure everything is good before I seal it up and bolt it all together. For some reason, I am able to shift it into gears 1-5, but I can't seem to get it to go into reverse. When I try, it feels like something is jammed and nothing seems to want to budge.

Any quick tips for things to check? Common noob mistakes?

Tranny setup:
Basically its a Mista Bone clone
1995 Si Tranny
ZC 1.346 3rd
VX 1.066 3rd flipped around serving as 4th (modified courtesy of Mista Bone)
EF 0.771 5th
OBX LSD

Thanks guys!