The real differences in 700r4/4l60/4l60e transmissions by year

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

JUAN88

Newbie
Joined
Apr 4, 2016
Messages
3
Reaction score
0
Location
Washington
Hi im 17, and new to this form and to owning a 88 silverado 2wd, i would like to learn about these trucks. The previous owner said he swapped a 5.7 350 tbi engine from a 95 tahoe but kept the transmission that was on the truck(im assuming its a 700r4). The transmission leaks alot of oil and im looking to replace it but dont know what transmission to go with since the engine is a 95 and the truck is an 88. The speedometer (moonie gauges) doesnt work at all but the other do i dont know why it doesn't work.Any help is highly appriciated, thanks in advance.
 

michael hurd

Stalker be gone.
Joined
Jul 30, 2012
Messages
1,876
Reaction score
603
Need more information.

Was the 1995 engine installed with the factory computer from the 1988 retained? Was the OE engine 5.7L, or was something else installed previously? IE: swap.

You can google the RPO code sheet and look in your glovebox or use the VIN and the information on the LMC truck website to decipher what engine was installed originally.

Start with that.

Once you have determined if the correct displacement engine is installed, then the transmission will need to be sorted out. There is a casting on the rear of the block, at the bellhousing flange indicating if it is 5.0 or 5.7L.

From 1988 to 1995, engines were largely unchanged. If the correct throttle body ( injector sizing ) and computer prom is in the truck ( as in not trying to run 5.0L injectors or prom on 5.7L ) then you should be fine.

1993 was the first year for 4L60E, as in electronic control.

The transmission thread might help you out a bit.
 

JUAN88

Newbie
Joined
Apr 4, 2016
Messages
3
Reaction score
0
Location
Washington
Sorry for the late reply, i checked the vin # and the truck(88) was originally equipped with a 350 5.7l. The engine that was swapped into the truck is also a 350 5.7 as for the computer i dont think is the original one because it has 89 c2500 ARW written on it like from a junk yard.
 

michael hurd

Stalker be gone.
Joined
Jul 30, 2012
Messages
1,876
Reaction score
603
Sounds good, if it was a simple engine replacement, then the wiring should not have been molested or modified in any way by the previous owner.

A C2500 could have come factory with a 4.3, 5.0, or 5.7 gas engine.

The ECM would be the same for 1988 and 1989, however the PROM inside will be different, for the different engine calibrations.

So, you 'likely' have the correct throttle body ( injector flow rates are different ) on that 5.7, you have the correct computer ( oe # 1227747 ) but we have no idea if the original for the truck PROM was installed in the replacement computer.

My gut feeling is likely not, however, I can't read or burn a PROM for you.

As far as the speedometer, I am not familiar with the circuit diagram, but I would start with verifying that the speed sensor is working, there has to be a test for that. A service manual would be beneficial in this case. Next would be the wiring from the VSS, disconnect both ends and do a continuity test.

In the early models, the VSSB or DRAC is internal to the cluster, so it is possible you have a problem with a circuit board or solder joint inside after that many years.

This also means, that simply swapping the cluster means you need to find one with the correct axle ratio and tire size in the vssb located in the cluster.

GM # 25085515 recalibration kit is no longer available.
 

JUAN88

Newbie
Joined
Apr 4, 2016
Messages
3
Reaction score
0
Location
Washington
So should i start looking for a 700r4 or one of the other two transmissions? Cause i read in a post that the 95 engine had to be a 4L60E because it was a single year, dont remember if it was for the vortec engines only. I forgot to mention that the previous owner told me that the speedometer was working fine before he did the swap, i will check the vss. Thanks
 

michael hurd

Stalker be gone.
Joined
Jul 30, 2012
Messages
1,876
Reaction score
603
4L60E for 1995 is a standalone year, the torque converter material and solenoid are different as is the valvebody. You could put a 1995 in a 1996 or the other way around, if you change the entire valvebody out and the converter.

The 1995 transmission would not work in your 1988 truck without a standalone aftermarket control unit to make it function.

There was also a 4L80E in 1995.

Unless you actually go under the truck and check the transmission pan to identify it, we have no idea what is in there.
 

SAATR

/\___/\___/\___/\___/\
Supporting Member
Joined
Dec 16, 2010
Messages
2,649
Reaction score
946
Location
Loo E Z an uh
The trans itself doesn't have any relays or fuses. Those are all on the truck. The trans itself has an output speed sensor, shift solenoids A and B, EPC solenoid, TCC solenoid, fluid temp sensor, PWM solenoid, and the PN position switch. I do believe that is all.

That's for 96+ only. Fairly certain that the 95 and before don't have PWM controlled lockup. Not sure about the other differences.

Sent from my XT1585 using Tapatalk
 

455fan

Newbie
Joined
Jun 14, 2016
Messages
1
Reaction score
0
Location
Maplewood, MN
Great thread. I do have a further question. I have a 1995 4l60 in my truck, not a 4l60e. It has the TV cable and I assume it is original since the computer and wiring are correct. If this is correct I assume any 700r4-4l60 from 1988-1993 should fit with no mods. It sounded like my OD blew yesterday, a bang and lots of grinding. Still moves in 1st but is parked till I figure out what will swap in. It is not worth the cost of a full rebuild. Thanks for any help.
 
Joined
Jun 18, 2016
Messages
3
Reaction score
0
Location
Georgetown Ohio
I just recently bought a 4l60e trans case 2 piece from a 97 Chevy and didn't know at the time I bought it the difference from 94-97 and was wandering if I could use the guys and wires from the 94 in the 97 casing my 94 4l60 trans cracked and I picked up the 97 trans case for 100 bucks and need the truck back on the road, if I can't use the guts and wires from the 94 how can I make the 97 trans work with the truck thanks
 
Top