Anyone want to swap diffs?

[beardydave]

I've got myself a 3.92 Sierra diff off eBay with driveshafts hubs and book uprights, but with the BMW gearbox I've got, the ratios will only give me a top speed of 111 in 5th, and first will probably be un usable.

Anyone in the fareham area with a longer ratio fancy a swap? Don't know if it's 7" or 7.5" yet as I don't know where to find the code.