Outer Limits 4x4 Board

Im trying to identify the Gearbox in my Hilux. The truck has been modified with a 253v8 and a five speed geabox. The ratios seem to be ok as it doesnt rev its head off at 100kmph and it sits on 2800rpm which i think is a little high. With the gearbox in the truck i can only see the number 5 on the side and nothing else to tell me what model of gearbox it is.

if you could put up a pic it might help mate.
is there an adaptor plate between the gearbox and transfer case if so it is prob a dyna box.

Thanks for that. I will crawl under and take some pics and post them tomorrow