I'm looking for a new extension housing, and the "local" dealership is kinda giving me the run around. I've found a site where I can get about any extension housing made for the 4l60/700R4... but there are several ones for the 4wd 4l60e. I measured mine, it's 4.5 inches, but even then I have 2 options, does it matter? or do I need get a casting number to compare to?

 

I'm pretty sure in your case you need to look at the amount of bolt holes for the transfer case side of things.

 

Both of the 4.5" extension housings that the site that I found have 6 bolt holes. (So do the 5" ones and the 5.5" ones). I think I'm just going to order one... there can't be that much difference I wouldn't think.