I've actually found out that the way to work out what kind of drive you are works through GTP.
< 1 post a day - FF
1-9.99 post a day - FR (which'll also be the most common)
10-19.99 post a day - MR
20 or > post a day - RR (which'll also be the least common)
If you want 4WD status then you will need at least 60 threads of any sort, to make the calculation for your torque distribution work.
Take the number of threads you have then take away 50, if necessary round to the nearest 5 (if you get a number ending in 3, 4, 6 or 7 round to 5, anything else round to a 0). The reason I do that is because GT5 will always set the torque values to the nearest 5 (discovered while tuning my touge Delta). This will give you your front torque value (it won't work below 60 threads BTW).
In my case, I have 87 threads so I take away 50 to get 37 which I round down to 35. To work out the engine position use the same concept as above with 0-9.99 posts meaning front engine, 10-19.99 for mid engine and 20 or > for rear engine.
This makes me a
35/65 F4WD type.
Even Praiano would be confused by that, I swear.
And we have now gone very off topic.