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I haven't got time to do all the searching, but there are a few. Powertrax I know makes lunchbox lockers for the ford 7.5 inch differential. Note that there aren't as many lockers available for the 7.5 as there are for the 8.8. If you're going to get real serious about your 4 wheeling, you might consider putting an 8.8 in the rear, and a D35 in the front.
8.8 isn't a direct bolt in. You need to relocate spring perches and shock mounts and stuff like that. Not difficult -- any axle shop. Been kind of hit and miss lately).