I don't think they had a lower bed option per say, just mid 99 they switched from using 4" blocks on the duallys to 2" after complaints from customers. People who had the higher trucks could swap them out after the fact. I had one customer that took even the 2" out! Also the 250s used a 2" block and the 350s SRW used a 4" block effectively giving you 2 different bed heights based on which you choose. Not sure what the 17"s duallys are using, but they definitely look taller, which is good for me, but not necessarily others.