Is 2006 AWD Mountaineer with axle code 45 "positraction"

[fourps]

Hi. I'm a newby here but 70 year old and have run into a stupid problem. I had the rear differential from my 2006 Mountaineer Premier (V8) with All wheel drive (AWD) and independent rear suspension rebuilt and then reinstralled it. The door says the rear axle code is 45, and I find tables that show that for the Explorer that is supposed to be a 3.55 gear and 8.8 AND I THINK it is open, NOT limited-slip / positraction. I filled it with about 60 or so ounces of Lucas Heavy Duty 85-140 gear oil and on a test run everything runs great. So, maybe I don't have a problem. But, I am not certain that this is not a positraction unit, and apparently if it is it would need Trans-X limited slip additive. A local supplier said to just put in the additiive as it won't hurt regardless what I have. But Ford says not to use additives you don't need and it is a hassle to empty some of that lube to make room for more additive if if it is not necesary.
I would value direction from someone who knows if that door code really applies to the Mountaineer and that it is NOT positraction. I've left to wonder, for example, because on eBay I find 3.55 differentials that they say are positracton and a "match" for my vehicle (by year and model, not at part number level).

Thank you for sharing your expertise.

 

[07EddyB]

I don't recall ever seeing any 4th Gen offered with a limited slip diff as an option. I may be proven wrong but I don't think it was ever available.

 

[Bill MacLeod]

There were only 2 axle codes for the 2006 model year.
45 - 3.55 non limited slip.
46 - 3.73 non limited slip.

3.73 was an option for the V6 engine only.

 

[fourps]

Thank you very much to both of you for your informed and prompt replies. It puts me at ease to stick with what I've done...and that will save some hassle for my aging bones which are already weary from getting the differential back into the SUV!