This typically happens because many sources incorrectly cite the basic empty weight, rather than an empty weight with typical equipment installed. From what I've found, it seems that listed useful loads typically fall between 1,350 and 1,400 lbs. I'm not seeing any 1985 models as high as 2,600 lbs gross, however. I'm not really sure where 450 lbs would go, between the basic empty and 2,600 lbs, to be honest. How about I add 120 lbs to account for the installed equipment, resulting in an empty weight of 2,265 lbs, and a useful load of 1,385 lbs?