I have a performance and specification manual for the P-47N that lists the maximum bomb load that can be carried as 1,600lbs under each wing and 500lbs under the fuselage for a maximum designed bomb load of 3,700lbs.
The P-47M manual is the same except that it can carry 1,000lbs under the centerline. That's 4,200lbs!
It doesn't sound like bomb loads like this were ever carried though.