obxs are OK, i personally know of a car making over 700 and it runs 10.0s all day long (for a year so far) and has no problems, u need to take the diff apart and check them when u get it, some of the bolts are not always tight and u need to loctite everything, im not saying this to be an ass but u may want to take the transmission else where, install a diff for someone qualified like u said should not be difficult