i made a post about this a few years ago, and have since upgraded the website and prices (used to be chevyduty.com)
i'm gonna try and make a sticky out of the part numbers for the 4-row conversion (if the mods allow it, if not, at least this should help some people wanting to do this one way or another)..in the mean time,here's all the info:
all my stuff, i bought from
www.classicparts.com, so these are there part #'s:
78-772 radiator rubber isolators (ya need 4) $6.95 apiece
78-845 top radiator cover $29.95
78-955 4-core 1 piece fan shroud $57.95
433730-4 core radiator auto zone part #, $174.99
(GM made a few different sizes of 4 core radiators, but this particular one works perfect with the part numbers above)
the top rad cover mounts to the rad support, and the shroud holding it in place, everything else, bolts, clips ya just re-use from your stock set up