looking for info on this tag. Thanks for your help.
Year, Make, Model, wheel base, Rear width. Etc.

 

C60 = C600 gas

C = 330 2V Medium Duty FT gas V8

U = Louisville Assembly Plant

809446 = 1966 numerical series, January 1966 production.

135 = 135 inch wheelbase

No paint code--truck is a special order and paint might have been part of that.

C600 = C600 gas, 20,000 lbs GVWR

691
6 = Black Vinyl
91 = Tilt Cab

A = New Process model 435 four speed transmission

62 = Rockwell model F-106NX6 single speed rear axle, 15,000 lbs capacity, 6.20 ratio
No front axle code--only optional codes are listed '64 to '69, so standard axle, at least 5,000 lbs capacity, no power steering

20000 = 20,000 lbs GVWR

164 3800 = 164 Certified Net HP @ 3800 RPM

551316
55 = St Louis District Sales Office
1316 = Special Order Number

OK model, WB etc is listed.

Rear width? From the outside of the duals it should be 8 feet. Maybe an inch narrower.

8 foot was the max width at the time. This truck was sold as a cab and chassis, so whatever equipment was mounted on it would be 8 foot wide maximum, with some small allowances for rubber fender flare/mud flap or similar stuff. That equipment would not be supplied by Ford nor of Ford manufacture.