Zig could probably give you the exact paint code for the paint used on the 228, but let me start by saying the GMC engine paint color is GMC orange! Not to be confused with Chevy V8 engine orange! Bear with me here guys, but does anyone remember the old mom & pop variety stores who used to stock engine paints in rattle cans? Gibson's here in E. Texas, Big K in Kentucky, Uncle Lee's in Tennessee, to name a few? Back in the day, you could go to the auto section and take your pick of any engine paint you wanted and each rattle can would tell you the color and range of years applicable for that color. "29-54 6 cyl all chevy grey" ""55 to present chevy V8 orange, except corvette" "32-39 Ford V8 green". The list goes on and on! Boy, I miss those days! Thank you Walmart!
I Dunno But , I like your truck ! . It's 1975 incarnate . I vaugely recall GMC's having fairly red engines , not Chevrolet Orange .