Auto Trans blows all the fluid out vent

Put a junk yard tranny in my truck 3 months ago and it run great. Had 70,000 miles on it. Today it blew out all the fuild from the vent tube. It was not overfilled and ran great till I went up a mountion and I smelled it and saw smoke out the back. Coasted down to the bottom checked, no fluid on the dip stick. Little Mon and Pop store only had 3 qts, I spilled half that trying to get it in hole with no funnel. would go in first gear but wouldn't shift. Called the roll back got it home. What would cause it to blow out like that?

Thanks, Staledale

Forgot, it's a 95 350 4wd 700r. It's in a 2 dr Tahoe, thought I'd get more replys here

first of all wrong forum

this is 99 up

but ill offer what i know anyway which may be limited

if you switch the pipes running to the radiator itll blow out all the fluid too

course if you do that it shouldnt have much power in drive

but will have full power in reverse

maybe check that?

Sorry about that, I see now the 99 and up post. I'll repost in the C/K. Thanks.