This may or may not help you. Although I wrote this for my '85 4Runner, the discussion on options and sources may help you decide what to do. There are drop-in, they are usually expensive. For some simple bracket mods, a high power alternator (140 amps) is pretty doable.

http://www.rocketcityrockcrawlers.c...ner%20Alternator%20Upgrade%20Project.pdf

Thanks,

Al

KI4Dxx
?85 Toy 4Runner: 35x12.50 BFG MTs, manual, Kenwood 2M, 140 amp alt, 26 gal aux fuel tank
'06 F-350 SRW 6.0 PSD XLT 4x4, manual, Yaesu 2m, 140 amp alt, 90 gal aux fuel tank, Air Ride air bags