I have spoken to Sims and Curtis. The only difference is that the Sims is less expensive. Sims is made in Canada and the Curtis is made in Worcester MA..... about 30 miles Northeast of here.. Curtis is $1700 plus 5% sales tax and the Sims is $1500 plus $80 freight. At such a close difference, I would like to know who makes the better cab and what the quality differences are. One down side of a soft sided cab is that when the soft sides are worn out, it cost about $500 to replace them. The Curtis hard sided cab is $2700. Lets hear some comments from the people that own one. The Curtis representative said that the hard cab is a big seller, but so far, I don't know of anyone that has purchased one. Curtis was nice enough to fax me the installation manual for both cabs.