We presently have a BH 3600RL but I am impressed with the layout of the 3670 RL, which we saw a prototype of at the factory at last year's rally. I believe it is based on the 3600 RL frame and has the same number of slides, yet there is a weight difference of 960 lbs and a pin weight difference of 220 lbs. All other specifications are the same, so could you please explain the weight differences? Thanks.