I have a 4400 with a slop bed on the back
http://www.flickr.com/photos/55chevytruck/5053727013/if you need any measurements checked for a comparison i am happy to assist.
Mine is a 4 spd manual 396 BBC - with a watson 2 spd underdrive - just getting it road ready now - had a little drive on Sat, and it is brilliant !
Does yours have shock absorbers ( Dampers) ?
Enjoy - it is a nice old truck I do love a big recovery.
