difference between bendex and delco boosters?

[roj2323]

hey guys,
i was ordering a brake booster from my local parts house "carquest" and i was informed that there are 2 different boosters that came on 71 trucks. what is the differance between the bendex and delo boosters and which one should i use?
if it matters i am putting it on a 69 gmc 1/2ton LWB 2wheel drive with a 307 engine. the front brakes have been converted to disk.

thanks,
ondrew