[2manycruisers]

I have a 2003 4.3 I'm putting in a Toyota. I've been planning to use a th350, but recently read the crank depth changed on those engines in 2001 and the matching trannies have a deeper bellhousing and different torque converter. I haven't found any specifics about the differences beyond that.

I know the pre-2001 4.3 will fit a th350 just fine. Is it possible to put a th350 behind this engine? If so, do I need any special adapters or parts? I measured the removable bellhousing on a 2003 Astro and a 1998 S-Blazer today and they appeared to be the same depth (~6 3/8") based on my somewhat crude measurements under vehicles in the mud and snow.

thanks!
David

[Crosley]

look at each input shaft of these 4l60e trans.

is there a polished end with O-ring on each input shaft?

Or does one input shaft have splines at the end with O-ring behind the spline area?

[2manycruisers]

I don't have access to the input shafts of the 4l60e trans, the ones I looked at in the scrap yard are still bolted to the engines.

What is the difference other than the location of the o-ring? Is one behind a deeper bellhousing than the other? Are the shafts the same length or different? It seems like if the crank depth was changed to require a deeper bellhousing then it is unlikely the shallower bellhousing of a th350 would allow the input shaft and torque converter to fit. But if the 4l60 with the deeper bellhousing has a longer input shaft, too, then maybe the th350 fits fine?

Dealing with auto trannies is new to me, so I appreciate any help on this.

Originally Posted by Crosley

look at each input shaft of these 4l60e trans.

is there a polished end with O-ring on each input shaft?

Or does one input shaft have splines at the end with O-ring behind the spline area?

[Crosley]

ON the shaft with splines at the end of the input shaft;

the bell is deeper, converter different, input shaft longer, pump stator shaft longer too... than the earlier design 4L60e.

Look at the bell housing.. top of it. Is there a hole at the the peak of the bell?

If your 4.3 is set up for the late design 4L60e trans as described above... then you need a crank to converter spacer and flywheel set up to bolt onto the early converter design t-350.

early trans design bolted to a LS series V8 engine uses the same set up with crank spacer and modified flywheel.

I do not work with 4.3 six cylinder engines, so I am shootin from the hip here

[2manycruisers]

Can you point me somewhere to follow up on the crank to converter spacer and flywheel modification you mention? I read that somewhere, but haven't been able to find it again.

I'll go to the yard tomorrow and look at the bellhousing. Do you mean a bolt hole at the peak of the bellhousing? I understand there are 2 different bellhousings for the 4l60e--is one for the older v8s and 4.3s and one for the gen III V8s (and maybe the 2001+ 4.3s?)?

I have wondered if they changed the crankshaft depth so that it would use the same parts as the LSx engines, but no confirmation on that. It seems to me that if the bellhousing is deeper, that would imply the crankshaft depth was moved away from the engine. But if it moved it that way, it seems like a spacer would not allow the torque converter to fit in a shallower bellhousing. Maybe the crank depth actually went closer to the engine, but the torque converter and other parts are all deeper, too?

Originally Posted by Crosley

ON the shaft with splines at the end of the input shaft;

the bell is deeper, converter different, input shaft longer, pump stator shaft longer too... than the earlier design 4L60e.

Look at the bell housing.. top of it. Is there a hole at the the peak of the bell?

If your 4.3 is set up for the late design 4L60e trans as described above... then you need a crank to converter spacer and flywheel set up to bolt onto the early converter design t-350.

early trans design bolted to a LS series V8 engine uses the same set up with crank spacer and modified flywheel.

I do not work with 4.3 six cylinder engines, so I am shootin from the hip here

[Crosley]

Summit Race has the crank spacer

clik here

Look around Summit for additional parts.

Probably additional help on the LS1 forums or Camaro - Firebird forums some where. I have no links for that

[2manycruisers]

I measured from the crank flange to the bellhousing flange on a pre-2001 4.3 and measured roughly 11/16" and tonight measured the same on my 2003 4.3 and measured roughly 9/16". It seems like about a 1/8" spacer would be appropriate, if my measurements are close.

I'll do some more searching on the spacer application. I thought it was on the LS1 forum, but I haven't found it again, yet. Does it use a stock flexplate, a modified stock flexplate, or a custom aftermarket flexplate?

[2manycruisers]

no bolt at the peak of the bell.

[2manycruisers]

the spacer for the LS1 is a 0.400" spacer. According to one article, the crank flange is approximately inline with the bellhousing flange on the LSx engines. The spacer would put it at 0.400" aft of the bellhousing flange. On my engine, the crank flange is approximately 0.56" and the older 4.3 would be approximately 0.78". I'm still at a loss.

Originally Posted by 2manycruisers

I measured from the crank flange to the bellhousing flange on a pre-2001 4.3 and measured roughly 11/16" and tonight measured the same on my 2003 4.3 and measured roughly 9/16". It seems like about a 1/8" spacer would be appropriate, if my measurements are close.

I'll do some more searching on the spacer application. I thought it was on the LS1 forum, but I haven't found it again, yet. Does it use a stock flexplate, a modified stock flexplate, or a custom aftermarket flexplate?

[2manycruisers]

Another thought on this--If the spacer puts the crank flange at 0.400" from the bellhousing flange and the pre-2001 4.3 crank flange is ~0.78" from the bellhousing flange, how did trannies interchange on those? Maybe my measurements are off, or maybe the LSx crank flanges aren't actually inline with the bellhousing flange like I read?

If I have to get a spacer made for this and move the flexplate forward an 1/8 or so, will the starter motor accommodate that? I checked aftermarket parts and they are the same for pre-2001 and post2001 engines, so I assume it's no problem.

Originally Posted by 2manycruisers

the spacer for the LS1 is a 0.400" spacer. According to one article, the crank flange is approximately inline with the bellhousing flange on the LSx engines. The spacer would put it at 0.400" aft of the bellhousing flange. On my engine, the crank flange is approximately 0.56" and the older 4.3 would be approximately 0.78". I'm still at a loss.