Flatire

question!
will a BOP 2004r bolt up to a Gen3 5.3?
I pulled the big block Buick, left the trans (2004r) in the car, dropped the LS in and can only get the bottom bolt on each side in.
Cheers

1968 Skylark

gofastwclass

iTrader: (2)

No, as you discovered the pattern is different. You will need to buy an adapter or use a different transmission.
For GM V8 rear wheel drive transmission bellhousings I'm aware of three:

• GM corporate V8 bellhousing pattern - fits small and big blocks plus the 90° V6 (4.3, etc). Will work with LSx engines using proper spacer and flexplate. No upper bolt hole.
• GM LSx V8 bellhousing which is a modified corporate V8 with a hole on top and a missing hole on the upper passenger side - matches updated pattern of LSx engines and crank spacing plus bolts to the oil pan for additional NVH suppression.
• BOP bellhousing - fits the Buick, Olds, Pontiac and Cadillac engines. Identified by two widely spaced upper bolts.

Flatire

Thanks! I just spent some time looking on Summit but didn't find one... any idea where i can find the correct adaptor?

vorteciroc

All THM200-4R transmissions have a multi-pattern bell-housing (Chevrolet and BOPCad).

No adapter is required, however a flat flex-plate and spacer will be needed to use a stock dimension 200-4R torque converter.
A custom converter is another option to mate the two.

ijimmy

Ill second that , make sure you beef up that2004r , and run a quality converter , [had a hews explode on me] , and adjust the throttle cable correctly , they really arnt the best for
huge torque , 4l80 prefered , after rereading your post I think you are probably dealing with a turbo 400 , thats the trany they came with [big blocks]

M33P

a BOP th350/400 will not bolt up to a LS. a 200r4 has both bolt patterns but would be found in the g-body buicks and others I assume.

jmd

iTrader: (4)

The 200-4R bellhousing was made two ways:
BOP only. Or BOP / Chevy dual pattern.

You could rebuild it into a dual pattern case.
You could run a bellhousing adapter plate (Chevy engine to BOP trans.)
The converter to crank will still need the spacer that's used for the TH350/TH400 converters. This was used on short crank trucks with 4L80.