Thank you all for your replies. The serial number is right where you said. I guess if I'd have looked around as I opened the door to crawl through the floor to scrape the frame looking for the number, well . . . thank you. Now, can anyone help me figure out what year this is? Serial # is 5C 5201 XXXXX. Or, a web sight with photos of this style cab. Thanks again.
55's have the chevrolet front fender badge below the crease. 56's have the badge above the fender crease. both have egg crate grills and no wind splints on the hood. 57's have wind splints on the hood and two ovals for a grill that attach to the otherwise identical fenders. all three of these tri-fives have only two headlights. if you have four headlights you dont have a tri five you have either a 58 or 59 and your badge might read Apache rather that 1500, 2500 etc. 1500 means 1/2 ton, 2500 means 3/4 ton (suspension) and 3600 means 1 ton. doors are interchangeable, cabs are the same as well. there are also large windows and small windows (rear) with, for some unknown reason, the large windows being more desireable, unless that is, you plan on chopping the top. then you dont want a large rear window since you'll be breaking too many windows. also on the 55's hood emblem, it's about 8" from tip to tip, where the 56's is about a foot or more. there is no difference whatsoever in sheetmetal from 55 to 56, they are the same truck. the 55 tri five is called the 55 Second Series because it came out half way thru the year. the 55 first series looks like the 49 (i think) thru 54 and is a completely different truck, as well as having 6volt electrical as opposed to the 12v '55 sec.series.