Posts #3 and #7 suggested the ford 9" which is bolt in and plentiful. You can swap the pumpkin to just about any gear ratio you want.
I have seen them go for as little as $150.
I have one for mine (traded some junk chevy parts for it)...if I ever get around to going and picking it up.
If you prefer the bolt pattern to match your front clip...a local machine shop can re-drill the shafts.