It's 1 1/2". All the old Chevy cars and pickups have it. It had to do with the hinge type mount used with the closed drive shaft. You could do it with a lowering block and deal with both issues at once. You'll have to lengthen the drive shaft.
Glad you had a good trip. I hope school goes well.

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain