Though I have no first hand experience with them yet, I have been trying to learn about them as much as I can. Full floats seem to be (debatedly) a stronger assembly than a Semi-float assembly. Here's a good quote I found when I searched the LCML archives: "A full floating rear axle is VERY similar to your front axle. Unlike a semi-floating rear axle which has the tires bolted to an axle shaft which rides on bearings and is held in place by a C-clip, a full-floating rear axle has a spindle which the tire is mounted to, an axle shaft with (or without) a flange goes to the differential and mates to the spindle through either direct mounting or a hub." and "Currently, if you blow the rear end or break an axle shaft, your day is done. With a full floater, you can break an axle shaft, disconnect it(or remove it) and continue on. The tire is held on by the spindle NOT the axle shaft." -J. Stone (whoever that is...) Sorry, I'm tired, so I thought this guy kinda summed it up alright.
Anyways, there has been continual debate on whether or not the FFs are actually stonger and actually have advantages and whatever--every one has their own opinion. But there are some facts to see there.
One thing to note is that the FFs seem to require a bit more maintainance than SFs. Supposedly the cone washers work loose and the nuts have to be re-torqued quite a lot...
More so if you run an auto-locker (like a deroit or a lock-right or somethin') in it 'cause the auto unlocking and locking just loosens those nuts right on up. A selectable locker (Electric, cable or ARB or somethin') is the only way to go for a FF. (IMO of course, some people have probably never had trouble runnin' an auto-locker in a FF, I just don't think it's a good idea--that's why I'm gonna run the J80 electric in mine
)
Price? Who knows. MAF just had a sale blowing them out for $495 plus shipping :-X . SOR has them for ~$450 again plus shipping. I called MAF and SOR when I was first lookin' for one and SOR qouted me $350 for shipping (from LA to Northern Utah
) Anyway, I am getting mine for around $450-500 (including shipping) from a local guy (shipping was cheap 'cause five of us went in to get them). They are kinda hard to find though--if I were doin' mine again for an FJ60, I would just swap in a whole 80 series rear--they're gettin' a little cheaper and are usually easier to find than the others ('cause they were an available factory option here in the US)
Oh and the difference between a 70 series and 60 series one is pretty much just width--though some 70 series ones came stock with rear disc brakes and some with dums, and 60 series never go disc brakes (also somewhat debated, but no factory disc brake 60 series axles have surfaced yet). If you are unfamiliar with the models, 70 series axle assemblies are a tad bit wider than 40 series axle assemblies and 60 series axle assemblies are a tad bit wider than 70 series axle assemblies and 80 series axle assemblies are a tad bit wider than 60 series axle assembies...
That reminds me, with all these rumors tha float around about how the FF rear takes so much more maintainance, it makes me wonder if the 80 series ones are like that as well? Any of you 80 series gurus wanna fill me in? Do they take a lot more maintainance than a SR rear end? Ya obviously the e-lock diff takes a bit more, but what about the axle assembly itself? Is the FF design of an 80 series rear the same (or extremely similar) to it's predecessor's FF rears? Any design changes any one is aware of?
Anyway, tclndcrz, nobody can be that jealous of me yet--mine still isn't here :
.... I'll be sure and post a pic of it when it finally arrives though--then you can be jealous and drool all you want.
Incidentally, look what was just on EBAY. It's a factory 60 series FF rear end with cable locker. Went for $1600 USD. (Yes, of course I bid, but it went WAAAAY out of my range.) I do know a place that'll get you one of these cable lock axle assemblies (front and rear), but it ain't cheap. They want $2000 USD for EACH assembly. Considerin' how RARE they are in the US, and how hard it is to get 'em, and how far they have to be shipped, that ain't too bad or a price for a complete assembly...
lol