These are not land pride but it will give you a pretty good idea price wise, and if you go to the vidos they give a pretty good explaination of how to use every they sell
Assuming that you want the rear blade for your L3800? I would really be looking at an 84" wide blade. Your tractor will handle that and you want your tractor width to be covered when the blade is angled over at 45*. You can get by with a 6 footer, but much happier with the 7'. Next question is which Land Pride blade, many different series to consider and do you want the blade to be able to be offset? I highly recommend that you purchase the heaviest duty unit that you can afford. The heavier the blade is, the stronger that it is built and the better that it will work for you. Light weight blades tend to just bounce over stuff and not really get much done. Yes the light duty units are less $$$, but you usually get what you pay for when it comes to NEW implements.