What is the most common diff centre replacements for a 1200 datto ute. I believe it is currently 4.something:1, but would like some extra legs for the open road (3.9, 3.8:1ish). Then, a replacement gearbox speedo drive mechanism to compensate for the diff. Any suggestions?

3.9 can be found in some datsun stanza's and bluebirds also i believe.

there is a 3.7 in one particular model of bluebird which seems to be as rare as rocking horse poo lately, theres a few guys on the site chasing 3.7 h165's.

3.9 will be the easiest to come by.

i dont think you can get replacement speedo drives, a reduction box may be the answer if you feel the 3.9 centre throws your speedo out too far

good luck

Thanks for the info on the centres. I had heard that there was a gearbox speedo drive from another species of datto that bolted straight into the 1200 type gearbox and compensated for the diff ratio change.