Running gear question / opinion

[mjensen]

So, I have a stock '69 GMC (well kinda...it's running a 327 instead of the stock 307) 3/4 ton. This was Grandpa's old rig and I LOVE IT! It's an old 4 speed that originally came with 4.37's (so I'm told). With it only being a few years old, by Dad backed it into a rock which split the rear diff cover and resulted in a blown rear end. After 2 months of looking, all him and his buddies could find was a 4.11, so they slammed it in and left the front as the 4.37. As you could probably imagine, it sucks driving in the snow but it's never met a mud puddle it didn't like

Now for the question/opinion. I've been toying with the idea of swapping axles, transmission (for a newer 5 speed), transfer case for a newer (maybe mid 80's). Is this a relatively simple swap? Or would this be a bad idea all together?

TIA
Mike