Outer Limits 4x4 Board

I have a 4runner running 33's which is a bit of a slug on the hwy but seems great in low range. No idea weather gear ratios have been changed or not but was wondering if diff ratios had been changed. Is there any way of identifying diff ratios from external markings on the case or do I need to dive in to find out?!

I'm looking to eventually drop in 4.88 ratios from the various posts I've read suggesting it's a good idea when running 33" or larger tyres but want to know where I am at before I do.

Chock vehicle safely. Jack one rear wheel clear of the ground so it can be turned. Mark wheel and ground with alignment marks. Mark drive shaft and diff housing with alignment marks. Select neutral. Rotate wheel that is clear of ground two complete revolutions counting drive shaft revolutions. Drive shaft revolutions counted is the ratio of the gears to one.

If auto locked, spooled or welded rear, jack both rear wheels and rotate wheel once rather than twice.