[Jac Mac]

One of my fellow GT40s members 'GT Bob' posted this compare pic of the BMW units.... but what you 'really' need is a housing which allows 9" heads, few outfits have/do make em in OZ & USA, but not in large numbers hence price is high, I built one, but don't do them on a commercial basis, I simply don't have the time.
With regard to a cooler I could understand that a 'clutch' type LSD might be warrant them due to the heat buildup, but with tru trac or other detroit lockers some means of feeding oil to the R&P contact area is probably more beneficial, but that's more of a driver call as to which unit he prefers.
Other factor that comes into play is the amount of hypoid offset, Ford 8.8 has similar to the BMW unit, 9" has about 0.75" more which can be handy if you want to get overall car height down.