I love lucas products. I used it alot, havent used any in the t-type because it hasnt run in a while but I will use it. I ran it in my 2.8L camaro and it actually gave me some power and smoothed the car out (none synthetic). It does stick to parts alot better, but that can also cause more drag on a engine. I would use it but thats just my .02.
The transmission additive actually helped some of the slip issues I was having on the 1-2 shift. I have read and seen some tests that show it clinging as advertised, but it also gets real foamy. Google search and you're sure to find some independent tests you can form your own opinion on. To me I think anything other than natural dino oil is overkill, but to each his own I guess.
Now for me I don't touch anything synthetic. In other cars I aklways have used synthetic with great results, but in this car synthetic seems to create oil leaks for me. I think it is too viscous (sp?) and get between seals.
Now I do use Lucas products and like their fuel injector cleaner very much so.
I put the Lucas gear oil in my diff and I put the posi lube in with it. The combination seems to be working well with each other.
I work with gear oil every day and I am very protective with my cars and the oil that goes in them. However, you are going to run into people that hate Lucas and then the ones who love it. I have never used Lucas in any of my other vehicles and have never used it in any engines. We all know what opinions are like.
So take what I have said with a grain of salt and make your own opinion.
I can tell you that I haven't had a problem with the Lucas with the posi lube that I added. You can risk your posi if you want but I didn't think it was worth the risk. My posi works great with both but then again my car only has 77,000 miles on it. I would recommend the additive. You can try anything you want but that is just my advice. Good luck