Hey guys,

So I've got an 1988 GMC Sierra I'm doing some work on, which originally came with a 700r4 transmission, but I swapped it out for a rebuilt NV3500. I'm using a new clutch, pressure plate, flywheel and slave/master cylinder, so I figure everything should work properly. For some reason the transmission basically temporarily blocks my shift on until I push in the clutch and hold it there for a second or two, then it lets me shift it into gear. 1st and 2nd gear are the worst, but 3rd, 4th and 5th are a little better.

To try and remedy the situation, I've replaced multiple parts just to see if it would help. I took the transmission out and had a mechanic look at it, and he said the synchros and other parts were new. Since then, I've replaced the master/slave cylinder, clutch, and pressure plate, but it still drives the same. To be clear, it shifts through all the gears, and doesn't grind, but when I'm shifting I shouldn't have to wait 2 or 3 seconds waiting and holding in the clutch just to switch to the next gear. As you can imagine, it's a pain in the neck to drive.

I'm at a loss here, and running out of ideas. How you ever encountered this problem before? Any help would be appreciated.