Center Section Differential Recommendation
There are 3 center sections.
741 (weakest, least gear ratio options)
742 ( middle of the road for strength, wide range of gear ratios)
489 (strongest, widest range of gears available)
Cass at
doctordiff.com can set you up with what you need.
You can put an ad here, you can look on EBay, Craig's list, Facebook market place