Received the following reply from Sargent...
We do not make a seat for your gs310 , however we can modify your seat in
our Custom Seat Services Dept. You send us your seat with detailed
information on what you are wanting to have done, we redo the seat and send
it back to you. We can add our Super Cell Atomic Foam, and change the shape
of the foam for more comfort. I will enclose a link to our CSS dept.
Print out the order form, fill it out and send it in with your seat.
There is a lot of information on this page, it may help you get exactly
what you are looking for if you read over it. If you have any other
questions, please email, or call us at 1-800-749-7328.