Dovetail plate?

I recently acquired a Meade 10" SCT. It has a dovetail plate on it that is about 17 1/2" x 4". By searching, I gather this is a Losmandy type plate. My mount take a plate that is about 1 1/2" wide and I am having a problem finding a mounting plate 17 1/2" x 1 1/2"... what should I be looking for?

Thanks for any help!

--Ken