Looking for any documentation '69 Barracuda Fastback

Yep - really sorry to learn about your dad passing. My dad was hard bent into early Mustangs starting around 1976 after fixing one up for my older sister who was about 25yrs old at the time.
Funny it seamed we all got off trying to figure out that car from the optional parts. A performance Mopar would usually always come from the factory with two muffler hanger brackets you can see from the inside where the back seat goes - one should be bolted thru and the other spot welded. If your car has the valance which is below the rear bumper it should have the two square cut outs for the chrome tips that came with a 340 or 383 motor.

Wonder if your dad had bought some shop manuals for it - or he could have bought the CD's they have now - that would help with the parts and build.

Any way good luck with it - it did look like a good car to build how ever which way you go and again sorry about your dad.

Lawrence