Will a 3rd gen drum rear setup bolt onto the 4th gen rear? (excluding brake lines)

 

just get a 4th gen rear with disc

 

No, different bolt pattern.

 

I belive the bolt pattern is the same.

5 on 4.75"

 

I believe the V6 4th gens had drums available through '96 or '97 so look for that housing. If it has the crappy 3 bolt flange that was used for drums on 3rd gens, g-bodies, and earlier S10's, then yes they'll work, but if you end up finding a 4th gen drum rear, just use those brakes; doubtful someone is going to charge $$$ for a stock drums setup.

 

I wasn't referring to the wheel bolt pattern, but the pattern on the end of the rearend housing. Drum brake 3rd gen cars have an odd looking housing end that sticks up a few inches above the housing; a disc brake (3rd or 4th) housing is a more conventional looking end that is more rectangular. Discs will only work on disc housing ends, drums on drum housing ends. Scott at SPeed Automotive sells complete 4th gen rears with brakes for around $350
http://www.speedautomotive.com