Knock $5,000 off the invoice price if you write a check for it. That lets the dealer still make a few hundred bucks and you walk with a $53k sticker truck for $42k.
Zero percent kills the $5 grand. If you have good enough credit to qualify for Zero percent, then chances are your bank (or the dealer) will do 4% for you on the truck. The dealer will make a few bucks on the loan, so he may get very competitive there and still let you keep the $5k rebate.
Pay attention here (here's where most people get lost with the Zero percent stars in their eyes...)
0%, 48 months, $47,000 = $979.17 payment
4%, 48 months, $42,000 = $948.32 payment
5%, 48 months, $42,000 = $967.23 payment
If you were looking at 72 months (you should be spanked for it if you were):
0%, 72 months, $47,000 = $652.78 payment
4%, 72 months, $42,000 = $657.10 payment
** as far as additional holdbacks, I would imagine that there are some, but 3/4 ton trucks usually don't have them as significant as the "transportation" units. 3/4 tonners are "work" units regardless of how fancy they are.
Hopefully, though, the current slump right now will net you a killer deal. Get on the net (www.supplierprograms.com or several others) and send out for competitive quotes to keep your dealer in line).