I have a 1984 GMC Sierra (K)2500 4X4 with a 4-speed manual transmission (5.7L V-8 350, 3/4 ton, utility service bed).

Out of nowhere, the transmission is making a loud banging noise when the engine is running/driving, no matter the RPMs. The noise stops when the clutch is engaged. No previous problems or symptoms.[:@]

Here's my question: Is the transmission interchangeable with, will the transfer case bolt up to, ANY GMC 4-speed manual topload tranny, 2WD or 4WD, or 4WD ONLY??

[&:]I have the Haynes manual, but it's not clear (crystal) from the photos. In the Haynes manual, it looks like the fill cap and drain plug on the 2WD tranny are situated differently than what I've got on the 4WD.

Any opinions?? This is my work truck, so time is of the essence! HELP!!