front axel swap

[wanted]

I recently bought a 70 gmc 3/4ton 4x4. This is my first experience with this this era of trucks.
It has a stock front axel with drum brakes and no power boost. I want to add disk brakes and power. I am assuming I can swap in another front axel with disks on it. I found a yard near here that has a 3/4 ton gm axel with 4.11 gears and disks but I don't know the year. My question what years will directly swap into my truck with no modification? Also, I know I need a proportioning valve for disks but would I also need larger diameter brake lines?
Any info on this swap would be appreciated.

thanks

[JIMs70GMC]

First off, don't throw that axle away I might need parts of it. Second the 3/4 ton front end is either another dana44 or a 10 bolt GM either will bolt right in. You'll need to get the appropriate brake hoses (the banjo fitting is different between the dana and GM). Third need a new master cylinder w/ booster and proportioning valve. What appears to be a proportining valve is not. I'm in the process of fixing my front drum brakes w/ parts from Jerry Moss. I'm being a little nostalgic about not upgrading but if the parts he sends me don't fix it I'll probably upgrade myself. You'll get more good input on this.

[jerry moss]

i'd stay with a dana 44 front diff, which i believe was used through 78. the later 10 bolt corperate front diff's will work but use smaller axleshafts. i'm using a 78 front diff under one of my trucks but be sure to check axle tube diameter. there are two diffeent tube diameters, 2 3/4 inch and 3 inch. your 70 is 2 3/4 and if you get one with 3 inch tubes, you'll need the u-bolts and u-bolt plates to match it.
when i put a disc front under my 69 i used a 75 diff and used adapters to match the brake line fittings at the frame connections.for the master cylinder/prop valve assembly, i used a complete unit from a 72 and again i used adapters for the brake lines. it's actually an easy swap once you get the adapters for the brake lines.