I ended up ordering a L2D body from lighthound. It fits and works except I have to have the stock LD10 tailcap screwed down really tight to get it to work. My stock LD10 body doesnt do this. Im going to order a LD20 body now that they're in stock and see if this alleviates the problem.
The batteries could be too long. Are they flush with the tailcap end of the body? They should be a little below the end of the battery tube. The metal ring in the tailcap has to touch the end of the body for negative contact.
Also when the tailcap is really torqued down and you unscrew it, the metal ring in the cap might come loose.