tire & differential questions

I know not all beleive in the off-roading capabilities of their box body Crown Vic. However...

I just put 225/75/15 heavy tread tires on my HUM VIC ;)
But I wanted to know if anyone has ever put
235/75 or 235/70 on their 85-88 with out problems.

And i wanted to hear some opinions on putting in a Torsen Trac T-2R
differential in. To confirm, I have its a 8.8 for the stock 87 RIGHT???

Yes, 8.8 is standard 28 spline