Frame differences in 67-72 Suburban?

[budnikguy]

Looked a bit and did not see anything on this topic...was wondering if there are any frame differences between a 68 and a 72 Suburban 2wd and 1/2 ton? Think I am going to do a frame off on my '72 and I have a '68 laying around...so thought I would do all my suspension work and frame strip and powdercoat on the 68 frame so I would not have to take down my '72. Then just swap my 72 Suburban tub onto the '68 frame when it is nice and perty.
So, help me a bit and lmk if there are any differences in the frames so I can ponder whether to do it this way...

As always thanks in advance for your knowledge and wisdom!

Adam