OK guys, I'm finally starting to get this truck resto going. As of now, I have a 95 Chevy Ext Cab SB with a 350 paired with a 4L60E. I'm planning to yank those, drop a 383 I'm going to build (block to go to shop soon) in it paired with a TH350.

I'm hoping that there are not too many problems with the crossmember for the tranny mounts. I'm not concerned about the motor just yet (using stock engine mounts location), but am trying to gauge how much work will need to be done for the tranny to fit right.

Has anyone done anything like this? I know the two trannys are not that far apart in length...

Oh yeah, and when it's done, all the boys in the mustangs will be wondering "What the H**l is in that thing?" :metal:

Here is a transmission dimension site that may help.

http://tciauto.com/Products/TechInfo/trans_dims.asp

The 4L60E was all electronic and the speedometer was controlled by it thru computer, so you will probably have to find a different speedometer. I think I would just rebuild the 4L60E and leave it. At least that way you have OD for longer cruises to help out with mileage with the 383.

Why not stay with a 4l60e, it would be just as strong if you build it up?

Why not stay with a 4l60e, it would be just as strong if you build it up?

I am kind of wondering the same, myself. In this day and age of fuel cost, the OD will help in the long run. Not to mention the first gear in the 4l60E is lower than the TH350's first gear was. It should support your attack on the pesky Fuuurds, better.

Plus then you can do a full rebuild on the one you already have. I would use B&M

There are outlets out there that are moving the same parts as B&M and you don't have to pay for their "Smoke and Mirrors". I and my Tranny guy have rebuilt a couple of 700R4s and the suppliers are moving the same heavy duty gears and planetaries as the big name boys, and you could end up with cash in hand.

I would stay with the overdrive to. If you do change to the th350, I think they make a conversion box for the speedo. Not sure though.

Well, the only reason I was going with the TH350 is that I got for free (for working on a buddy's boat motor). It was rebuilt many years ago, and run for a couple thousand miles, then yanked (fluid is still red). It does have a unibell housing, so I could use it for BPO applications if I was adventurous (read crazy :) ). I was thinking of building the truck without the need for a computer. Keeping the 4L60E won't let me do that.

My other option is to build a completely computer controlled motor/tranny combo. I am not opposed to this, and could probably get better HP, torque, and general performance from this setup.

Like I stated, the tranny is good, essentially brand new, with heavy duty parts. It is more of a "Can I do it" than a "I need to do it this way".

Thanks for the input, I'll keep you posted...

You can do it but the cost doesn't always justify doing it. Loss of mileage, buying another speedometer, speedometer cable, tearing the dash apart to try and retrofit everything, and then will the computer act properly because you have speed sensors, etc that all work in conjunction with the engine. I don't think it would be worth it. And for a tranny being rebuilt "many years ago" then yanked, you have a 50/50 chance of something not going wrong. Just my $.02 worth.

Kevin

I would continue the computer lineup that the truck now has. Your investment will be large to get them changed over to the older style components. I would estimate that a rebuild on the 4L60E will be less, in the long run.

Yeah, the more I think about it, I like the computer controlled system a little better. I really like Edelbrock's upper end kit with the injectors and fuel rails.

Last question: How much horsepower can I build a 4L60E to stand? The 383 will be no slouch (400+ hp).

I have a couple of 700 R4s built to take about 500 HP. I have one behind my 383 in my 84 GMC, and it definitely ain't no slouch in the street, as a matter of fact the truck has seen speeds to better than 135 and still pulling strong. The other is behind my daily driver and although it is not a Mustang killer, it does handle itself. The 700 R4s are the predecessor to the 4L60E trannys, just does not have the computer control. Also, the 4L60E behind the Impalla SS LT-1 that I have is standing up real well. You need to find a good tranny guy and use his sources for the heavy duty parts.

The Camaros and the Vettes with the LS-1 and Ls-6 motors were sold with the 4l60E trannys. These motors are capable of making 500 HP with just simple tuning and cam changes. Most of the owners of them worked the Holy Hell out of them.

A 700R4 is a great tranny and a 4L60E is the same thing, beefed a little, and all electronic.

Cool. Sounds like the better way to go anyway. Anyone need a TH350?

Just kidding...

Thanks again for all the advice!