I want to get a rear locker for my 84 f150 w/ a 351w, i was wondering what you guys would reccomend as the best one to get. Also how can i tell what rear end i have? Thanks.

 

Look at the rear end, if it has a removable differential cover, it's an 8.8" rear. If it doesn't, it's a 9" rear.
If you want a good full time locker, I'd get a Detroit Locker. They cost some $$, but if you break one, you've done something stupid. If you want good road manners, I'd try a selectable locker like an ARB air locker or Eaton electric locker. Either one lets you turn it off for the road so you don't get that tire grab when you go around a corner like you get with a regular locker.
You might even try a limited slip if you don't want a full on locker. I had an Auburn limited slip in an 83 F-150 and it was pretty decent, but if you do some nasty four wheelin, it can leave you wanting more.

 

Most likely you have the 31 spline Ford 8.8 rear axle. It's a good all around axle that can take a good amount of abuse. I have a Power Trax No-Slip locker in my 84 F150 4wd and I love it. It's not as strong as a Detroit Locker but works just as good. It uses the stock carrier, but replaces the spider gears. I am not into extreme 4 wheeling so it works great for me, it's plenty strong under my right foot. I have pulled out a few tree stumps and a couple stuck vehicles with it and it has held up great. It has a tendency to chirp the tires if you step on the gas hard when cornering, other than that the Powertrax gets a thumbs up from me. I know a couple other people who use em too and they love em too! I ordered mine from Napa, it cost me 460 bones out the door, money well spent.

 

I have the Power Trax Lock-Right in my 8.8, it was cheap (if you can call it that ) around $200. I use my truck in the same manner as Pkupman82 (stumps, stuck cars, light snow and mud). I am happy with the performance, it is kinda harsh on the street but once you get used to it, it's not to bad ('gotta pull the clutch in or stay on the throttle around corners, one or the other). Big difference in traction over the open rear!

I understand that the No-Slip is a smoother product. The advantage of the Power Trax is that installation is fairly easy since you do not have to remove the carrier (usually).

Now to install that limited slip in the front diff

 

I was just looking around on the internet tonight and found the detroit E-Z locker, has anyone used that one? Is the install easy? Strong? Any opinions on it would be greatly appreciated. Thanks

 

I understand the Detroit EZ locker is basically the same thing as a Powertrax. I don't know anyone who runs one, it seems to me from experience, the insertable locker is a good design. Although not as strong as a full carrier replacement style locker (Detroit). I plan to swap out my stock 3.08 gears for a set of 4.10s and a Dana/Spicer Trak Lok for the front. I also plan on installing a set of 33x12.50 MTs.