ok so i had to torch off my backing plate, and drum brakes setup today. so all of the drum stuff that had come with my 70 is junk. so i figure if im gonna put money into brakes i might as well go for discs..... so im basically going to be re building my entire brake system.... so i need to know what exactly im going to need to run the setup.... i know im going to want a M/C from a large truck/car that had 4w disc's then im going ot need a combo valve right??? if so whats a good application to source one from??? and lastly, what type of caliper, caliper bracket, and rotors will i be using that will BOLT up to my existing mounting flange???? woulda searched but well you know...... the D70 is out of a 79 F350 SRW

You shouldn't need a combo valve, just a proportioning valve, go with one from summit for like $40. You should be able to use your existing master cylinder, just remove the residual pressure valve from the rear port on the master cylinder. I couldn't tell you what brackets to use, but someone is making weld on brackets for like $30pr, you use k20 rotors and either S10 or full size chevy calipers.

well i was searching on ebay last night and i found a set of bolt up caliper brackets for a D60, they bolted up to the backing plate flange. would i be able to use that???? it was set up for the chevy calipers. is the D60 backing plate flange set up with the same bolt pattern as the D70 backing plate???

60 and 70 caliper mounts are different. Here's a link to a full write up for 70 disc conversions.

http://www.off-road.com/toyota/tech/dana70discbrakes/

well i read through the article, and its good. i sent off any email to great lakes offroad to see about getting a set of the bolt up brackets, but im currently trying to figure out what caliper to use that will have ebrake ability.... and mount to those brackets and fit the rotor. any more info you have would be great....

No parking brake: 79-87 Chevy truck half ton 4x4 calipers
Parking brake : 76-78 Eldorado rear calipers.
And then the typical 79-87 3/4ton front chevy rotors, which is identical to the 78-9 ford D60 rotor (possibly other years too but this was the only one i had to compare), except the chebby one is vented & the ford one is not.