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Will 700-R4 from 2.8L fit on 4.3L?

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21K views 14 replies 8 participants last post by  Crosley  
#1 ·
Hey, I've got a 700-R4 from a blazer with a 2.8L engine and I have a blazer with the 4.3 that needs a transmission. I assume the r4 from the 2.8 will bolt right up to the 4.3, but one of my friends told me that there are tons of different bolt patterns forthe 700-R4. So anyway, will the700-R4 that came off the 2.8 fit on the 4.3?
 
#3 ·
M&M CUSTOM said:
No it will not fit, the bolt pattern for the 2.8 V6 is shared with a few other 4 cylinder engines, a few other V6 engines like the 3400 and 3800 and not much else.
Actually, this is the GM metric bolt pattern which is used on most of the current GM engines. All 60 degree V6 motors (2.8. 3.1, and 3.4 displacements) plus the Series II and newer Buick 90 degree V6 motors (older Buick V6s used the BOP bolt pattern). Also the Northstar uses a version of this bolt pattern. One bolt is off and the top of the bellhousing needs to be notched to clear the starter, but the S10 700R4 is the usual trans for converting the Northstar to RWD applications.

Of course, as you correctly point out, the 4.3 uses the normal Chevy bellhousing bolt pattern.
 
#7 ·
joe_padavano said:
What, to adapt the metric bolt pattern to a Chevy? Why? Correct 700R4 transmissions are plentiful and not expensive.
You have a good point. I can get a 700r4 pretty much any day for 1-200 bucks...Im sure I'd probably be paying at least 50-100 for an adapter. Aside from price, would the power of the 4.3 burn up the 2.8 tranny if I were to find an adapteR?
 
#8 ·
Forget about the adapter.... many traditional bell TH700R4 transmissions are available.

The 4.3 engine crankshaft cannot accommodate the 2.8 torque converter pilot. It's just totally different. You could swap TC in and out but then you run into input spline count issues depending on year.