C 30 9 foot Bed Drawings

[c20 diesel]

I have a C30 133 wheel base. missing the 9 foot step side bed, have not been able to find a 9 footer.
Belonged to the city when new. had a service body. when I bought the C30 with no bed. Tried to put a fleet side long, most lined up good 6 inches to short in front. added 6 inches to the front don't look to bad.
Question how do I tell if Factory cab chassis, or was the bed removed &
replaced with a Service body.
At one time I founded factory drawings [prints],on the internet got lost For the 9 foot step side bed not been able to find drawings.on the net again
I think I can build the be.
Need to find drawings or get 9 foot measurment.