Clutch problem for '67 with a ~2000 Silverado transmission

[TruckintheBoro]

Hi Folks,

My mechanic installed a new engine (350) in my '67 C10 last Friday. I decided to replace the clutch at the same time. The guy I bought the truck from had installed a 5-speed manual transmission from a ~2000 Sliverado 1500 that's been working great the seven or so years I've had the truck. The prior owner said (and I've confirmed) that that transmission was the NV3500, and was used in the Silverado 1500s from 1999-2006 as well as the s10 from 1993-2003 for the trucks with the 4.3L v6. He said the clutch pack from any of those should work.

So I bought the clutch pack for a '94 S10 from Napa (NCF 1104168) which came with a new release bearing. The engine builder installed the clutch pack on the flywheel (I think I'm saying that right). And then my mechanic installed the release bearing from the new clutch kit when putting everything back together. But once he was done, the transmission crunches going into reverse and the clutch doesn't engage until the bottom of the clutch pedal's range. At that point, my mechanic noted that the release bearing that came with the new clutch pack (and that he installed) was substantially thinner than the one that came off the truck. But he also wondered if the clutch pack exactly matched what had been on there before. I contacted the engine builder and he said he compared the new clutch to the old pretty carefully when he did the replacement and they looked the same. He thinks the issue is the bearing, which should be the one for a '67...i.e. should match the truck year not the clutch year.

So, I'm picking up a new release bearing today (matches the '67 and looks like the one that was in there before). The question is should I pick up a clutch pack for a ~2000 Silverado as well? Once my mechanic has the transmission out to put in the bearing, that would be the time to swap out the '94 S10 clutch pack for one that more closely matches the original transmission. But if it's obvious to those who know (not me!) that the clutch pack is fine and the bearing's the issue, then I can save myself a lot of hassle.

Thanks.