Hello. I picked up a 1998 b4000 automatic with a bad trans everything I’ve read says it should have a 5r55e so I got trans from a rebuilt 98 explorer 5r55e swap it out no plug issues went smooth.

The issue is from 1st gear from take off if I’m really heavy into it, it will redline and not shift. If I’m driving normally and shift just fine and drives fine. I’m wondering if the truck had a 4r55e due to the fact 1/2 on 5r’s using over drive to “make it a 5 speed”?

no codes etc. Truck has over sized trans cooler ran with factory cooler? I didn’t do this a shop did it before I got the truck. They did a bunch of work and the truck lasted maybe a 1000 miles. It looks like they might’ve swapped in a 4r44 and swapped bell-housing over. I can’t find any information on the trans that came out. Only thing I can see is the bell housing was pulled off and has gasket maker on all the bolts.