The 4L60E is a square pan and the 4L80E has a much bigger pan that is not flat or square near the back, and it also does not have a 360 degree
bellhousing like the 4L60E. As far as the front differential goes, I would put synthetic in it also. GM is soon releasing a service bulletin that states if you live in an area that could reach -10 degrees, you are suppose to use sythetic in the front because the 80/90 is not flowing well during cold temps and is wiping out pinion bearings. Better safe than sorry.

 

I forgot, for the transfer case. If you have Auto 4wd. (Auto 4 button on the dash), you should use GM Auto trac II fluid. It is bright blue in color. It will take exactly two quarts

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by LS1NOVA:
<strong> I forgot, for the transfer case. If you have Auto 4wd. (Auto 4 button on the dash), you should use GM Auto trac II fluid. It is bright blue in color. It will take exactly two quarts </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">huh?? i changed mine and just regular looking atf came out so that is what i put back in. do you have any more info on this? i do have the auto 4wd.

 

i just did my rear diff and it took a little over 2.5 quarts

 

Gm came out with autotracII to inprove the life of the clutches in the t-case. It is just an imroved fluid and comes factory in the new trucks with Auto 4wd.