Alright, gonna start from the beginning. First part may be irrelevant but here goes:

DOHC ZC with ZC trans. Going down a hill in 3rd gear at maybe 35-40 mph. Car shakes like mad and the shifter pops into neutral, but transmission is stuck in 2nd gear. Limp it home, all the while my clutch is fully operational (i.e. taking off in 2nd no problem, no slipping, shuddering, etc.). Took trans apart and it realized it popped into two gears at once, then stuck in 2nd.

Now, I just picked up an SI trans (L3-9000). Put it all together without a hitch, trans slides in easily, etc. When i have the whole friggin car back together I notice the clutch lever where the cable attaches has MAYBE half the amount of play and when I lift it up as far as it will go there is a metal tap and it just stops and wont go anymore. Put cable on and start it up anyways. Adjust cable numerous times and clutch wont disengage. It is stuck engaged.

If I turn the car off and put it in any gear and start the car, wheels spin and clutch doesn't slip, all gears work fine no noise or anything. Took trans out again to check throwout bearing, operating perfectly and no noise or play. as soon as I slide trans back in, same issue with clutch cable lever, has only half the play that it should and wont disengage clutch. I'm lost and tried searching to no avail.

 

Did you inspect the clutch when the trans was out? Sounds like a spring may have popped out of the clutch and is wedged between the pressure plate.