Unfortuantally, I do not know what kind of milage the 4bt gets.. Always thought it would be too small, too heavy, and not enough power for what it offers. Its also almost cheaper to go with a 6bt. I am looking to get somewhere between 20-28mpg from the 6bt, that will be a large improvement over the 8-10mpg I was getting with my Toyota I-6.
The portals are very expensive.... I ponder weather or not I need something that beefy... I think though.. that in the snow.. it would pay off not to get hung up on anything.. or bash the diff on an unseen rock. and I wouldent be using the diff to plow mud, snow, rocks, or anything else that you would normaly do with a diff that sat 4-5" lower. In the end.. If it will do what its soposed to do, and not gernade, I think it will be well worth the extra $$$$ now, then shredding my toyota axel and buying something else later. Ill lose twice. Once on the axel I could have sold, once on the axel i bought to replace it, and then the modifications needed to convert that axel to fit it under my landcruiser.
Thats where these really shine IMO, you bolt them on.. no extra fabrication, no guess work, just drop your current axels and install your new ones.. get er done in a day. Since I dont do too much fabrication work myself, especially when it comes to the geometry of the suspension, You would figure somewhere between a min of $75-$125 an hour by about atleast... id figure a day or two for work.. so.. 8-16hours.. .. about 1500. Then you have to wait 3-6 weeks out before they can even look at what you want them to try to do. Not too many people want to work on an 80. then times that by 2, one for front one for rear.
so just thinking out loud...
5K for the axles, 3K for the fab work, change out the 8lug to toyoa 6lug/adapter
and you have about what it would cost you for a set of stock portals. Sorry its so long.. typing out loud helps me see things I would otherwise miss.
Bah.. its still a lot of money.
Ill keep you posted... Ill know by the second week, next month what I will do.