Just A Few Questions From A Newbie

jsucci · August 26, 2009

Hi, im new to the forum. Just bought a 95 GMC 1500 Ext. cab 4x4 auto with the 5.7 liter engine. My 1st question is how do i find out if i have the 4l60 or the 700r4 transmission. I found the model number on the transfer case, its the np 241 c but not sure of the transmission. Second question is if i put the truck in 2 wheel drive it wont move but if i put it in 4 wheel it will. could it be the transfer case, i can hear the transmission moving, or could it be the rear end? thanks in advance for any help.

MS3DALE · August 27, 2009

You have the 4L60-E (Which is basically an electronically controlled 700R4) If you look in your glove box on the SPID label you will see RPO code "M30" which is the code for the 4L60-E transmission.

mattgob86 · August 27, 2009

Well to figure out your problem, put the truck in 2wd and in gear, and either you look under the truck to see the drive shaft or have someone else do so and if it is spinning then the rear end is toast, if it is not spinning something in the tranny or transfer case is jacked. My prediction something is wrong in the transfer case but if the rear end is jacked then you should not be driving it till you get that fixed.

jsucci · August 27, 2009

Well to figure out your problem, put the truck in 2wd and in gear, and either you look under the truck to see the drive shaft or have someone else do so and if it is spinning then the rear end is toast, if it is not spinning something in the tranny or transfer case is jacked. My prediction something is wrong in the transfer case but if the rear end is jacked then you should not be driving it till you get that fixed.

thanks for the info on the tranny, that was the one i thought it was.

im hopefully gonna be getting a transfer case this weekend for it, that is my first guess at whats wrong, ive had rearends go out in other trucks and it dont seem like it did when that happened.

jsucci · August 27, 2009

i had the truck jacked up in the air and the drive shaft spins but the wheels go real slow so im assuming its the rearend. how do i know what rear end i have in the truck, not sure if theres more than one for it or what ones will work with it

MS3DALE · August 27, 2009

i had the truck jacked up in the air and the drive shaft spins but the wheels go real slow so im assuming its the rearend. how do i know what rear end i have in the truck, not sure if theres more than one for it or what ones will work with it

Yes,There are more than one,You could have either the 8.5" rear-end,or the 9.5" rear-end.

Again,Look in your glovebox on the SPID label,If you have "F44' you have the 9.5" rear-end (F44 is the code for the heavy-duty chassis pkg.) If you do NOT have F44 then you have the 8.5" rear-end.

Then you need to determine what gear ratio you have,and if you have the locking differential....."G80" is the code for the locking diff.

On the gear ratios....GU4 is 3.08 - GU6 is 3.42 - GT4 is 3.73 - GT5 is 4.10.

jsucci · August 28, 2009

i had the truck jacked up in the air and the drive shaft spins but the wheels go real slow so im assuming its the rearend. how do i know what rear end i have in the truck, not sure if theres more than one for it or what ones will work with it

Yes,There are more than one,You could have either the 8.5" rear-end,or the 9.5" rear-end.

Again,Look in your glovebox on the SPID label,If you have "F44' you have the 9.5" rear-end (F44 is the code for the heavy-duty chassis pkg.) If you do NOT have F44 then you have the 8.5" rear-end.

Then you need to determine what gear ratio you have,and if you have the locking differential....."G80" is the code for the locking diff.

On the gear ratios....GU4 is 3.08 - GU6 is 3.42 - GT4 is 3.73 - GT5 is 4.10.

thanks again for the information, its been really helpful