Automatic Transmission Identification

[madcarpenter]

Can anyone tell me how to identify the tranny on my 1989 gmc sierra 1500? I'm pretty sure its the 4 speed overdrive, just want to make sure before I make any adjustments. Its acting like it isn't certain which gear it wants to go in when I'm running 55-60 mph with no load. Seems to be shifting up and down a lot. I think theres a way to find out by counting the bolts on the tranny pan.

 

Anybody?

 

Thanks,

 

Jafo

[gmtech4]

you most likely have a 700R4 ,it has a square pan,if you have a flare to neutral when it should be going into 3rd ,you need a new 3-4 clutch assembly and a possible full rebuild ,there are no adjustments,and of course changing the oil and filter will not help

[Draenor]

 

1 Powerglide 14 bolts

2 TH200 Metric 11 bolts

3 TH350 13 bolts

4 TH400 13 bolts

5 TH200-4R 16 bolts

6 TH700-R4, 4L60, 4L60E 16 bolts

7 4L80E 17 bolts

[madcarpenter]

I looked at the pan and counted 16 bolts, so obviously the 700r4. An interesting development: I spoke to the P.O. and he stated that the tranny was rebuilt about 12 months ago and he produced the reciept. Good call Robert. A total rebuild. The P.O. also stated that he (personally) installed a new torque converter apx 6 months ago.

Heres another thing. I had my father drive the truck while I really listened and now I dont think it its the tranny at all. It seems that the engine itself is skipping/stumbling at 55-60. Almost like a hiccup, then it goes. I'm sorry I sound like such a putz but this is my first gmc/chevy truck. I've always owned fords. No real preference, it just worked out that way. Are the older chevys prone to this skipping and stumbling hesitation thing?

 

Thanks,

 

Jafo

[Mike G]

Should not be any skipping or stumbling. It soulds like it may be a fuel delivery problem. Does it happen all the time? Have you done a tune up yet or put a new fuel filter in? This may sould odd, but check your plug wires and how they are routed. Sometimes if they are old they tend to arc across each other. Make sure they are good and routed nicely.

--Mike

[Scorps]

 

1 Powerglide 14 bolts

2 TH200 Metric 11 bolts

3 TH350 13 bolts

4 TH400 13 bolts

5 TH200-4R 16 bolts

6 TH700-R4, 4L60, 4L60E 16 bolts

7 4L80E 17 bolts

 

Thanks for posting that, did a oil change today and shes a number 6

 

Might have to have it rebuild and stuff it in my malibu