I recently purchased all of the parts necessary to swap a 700r4 out to a world class T5. I had the speedo gears in the T5 changed to match my 373 rear end. Tranny came back with no fluid in it. I saw here that it takes ATF? Which I assume is automatic tranny fluid, is this correct? This may be a dumb question but I don't want to make that mistake, what tranny fluid goes in there?

 

Yep. Any Dexron Mercon III or better.

 

ATF Dex Merc III
Mobile 1 is popular
you can also use redline Manual trans fluid it is designed for manual transmissions designed to use auto trans fluid.

Your best bet is to install the trans remove the fill plug put a drain pain under it and fill by dumping in the shifter hole. Much easier cap off when it comes out the fill hole.

 

You're in a cold climate. Just run cheap parts store Dexron-Mercon (Dex-III.)

I like filling from the shifter hole too, but some consoles are more hassle than others.