Considering a Transmission swap, need some advice

[zieg85]

I brought home another one today.  It is a 1991 Suburban Silverado C20 with a rebuilt automatic overdrive.  The previous owner rattled off a bunch of things that were done to it most of it went in one ear and out the other.  It got me to thinking that it would be a simpler swap in my 1985 C30 with the TH400.  I am not a fan of automatics but I am thinking it makes more sense to keep it an automatic and keep the wife a little happier.  Couple of questions I have before I crawl underneath it are:  Is there any length difference in the transmissions?  Being a 91 does it have a VSS instead of the speedometer cable?  If it is VSS how hard would it be to change over the speedo electrical connections in my 85, the 91 cluster has the 999,999 odometer and trip odometer which would be nice to have.  Probably need to have my carb redone so it would accept the TV cable.  What about the lockup feature?  What other things need to be done to make the swap work?  Any thoughts would be greatly appreciated.

[VileZambonie]

I'm kinda confused as to what exactly you're swapping into what? 

What trans is in it now? 4L80E or 4L60?

[zieg85]

I'm kinda confused as to what exactly you're swapping into what? 

What trans is in it now? 4L80E or 4L60?

Don't know what is in the BURB, thinking he said 4L80E, but whatever it is swapping it into my 85 C-30 which now is a TH400.

[VileZambonie]

If it's the 4L80E you'll need the electronics, wiring harness, computer, sensors etc or it won't work. If it's a 4L60 it'll be less work.

[zieg85]

If it's the 4L80E you'll need the electronics, wiring harness, computer, sensors etc or it won't work. If it's a 4L60 it'll be less work.

How do I ID the trans that is in there?

[zieg85]

I googled the trans and I think if it get my butt underneath it should be very apparent which one is in there.  I pulled the service parts id off the glovebox...oops it said do not remove.... anyway it lists RPO code for the trans being the MT1  MXO, but neither actually ID the trans itself according to what I could find.  I will report back tomorrow with my findings.  Thank you Vile.

[VileZambonie]

I think you'll find it's a 4L80E

[zieg85]

I think you'll find it's a 4L80E

You are right, what is it gonna take to put it in the place of a TH400 in my 1985 C20??  It is coming out of a 1991 Suburban with access to everything wiring wise.  Thanks in advance.

[VileZambonie]

Is your engine already TBI?

[zieg85]

Is your engine already TBI?

No the 1985 C30 is the way it left the factory with a 4 bbl.

[Captkaos]

You need the ECM and adding the TBI from the current motor will add drivability.

[zieg85]

You need the ECM and adding the TBI from the current motor will add drivability.

TBI is not possible, I have to return the engine, other than that everything else is mine.

[Captkaos]

have to return the ECM too, the 4L80E needs the ECM to shift.

[VileZambonie]

This is the cheapest stand alone I've seen http://cgi.ebay.com/ebaymotors/Keisler-SimpleShift-4L60E-4L80E-AODE-518-Controller-_W0QQcmdZViewItemQQhashZitem230afb24ffQQitemZ150508086527QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[zieg85]

have to return the ECM too, the 4L80E needs the ECM to shift.

He is getting the engine back with the only wiring going to the TBI.  Went to start it to put it on the trailer and someone had robbed it so we took it off his other truck that this engine is going into.