correct brake master cylinder?

[Banjo]

Ok, got my kingpins greased, took 'er for ride. Still not happy with brakes and it struck in back of my mind I'd had to add fluid a month or so ago (still only neighborhood driving truck as I'm working through kinks), which is always a concern, so I pull hood and there's fluid all around the back of the master cylinder, although level has only slightly decreased (almost immeasurable), but this made sense to me because brakes had been trying to lock up sometime and taking considerable effort (power drums in '68 1/2 ton), so all this adds up and I figure need new master.
So, off I go. Well, the lines were on engine side of master on one that was on there (no telling what year it's out of). So, rather than make new lines, I look for power master booster on engine side too and find one at advance (about $18 or so reman). Here is my big question/concern. The computer didn't say "disk" or "drum" only for power brakes and I had them look up 1978 (because earlier years I was running into fittings on fender side and I didn't want to have to bend or make new lines.
So, I'm concerned what I bought. It is Advanced number (Orig Equip Reman #10-1854) and bottom underside of metal casting is stamped 29903 and near back where mounts to booster (still on bottom) is stamped GL-14. there is additional metal stamping on fender side under of master that says 13470. I know there is a difference between drum and disk master cylinders, but don't know that I could visually tell and their computer didn't specify. Did Ford have power drums on 1978 1/2 tons, or do I need to go back and get the '68 one they had in stock and bend the heck out of my lines (or make new ones)??? Banjo.

[Banjo]

forgot to mention, yes, I did check bore in back of old master cylinder and new reman one, both 1", Banjo.

[AlleyCat]

Banjo, go back and get the one for a 68 and make up the lines.72 was the last of the front drum brake F100's.

[Banjo]

Well, I'll be dad-gummed!!! Thanks, banjo.