I used some stuff from the FLAPS called Blue Devil or something like that for cleaning out my radiator and coolant passages on my '57. I couldn't believe how much rust and crud came out. It ran much cooler after that.

'64 swb stepside (gone)
'57 1 ton
'53 phone truck
'59 swb
'46 1 1/2 ton
'68 swb gmc