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We are glad you have joined us! You will find some very friendly & helpful members here...so please feel free to ask questions.
What I found was a Tiffin Model Product Archive
that goes back to 2005.
The Allegro BUS was 38 or larger in 2005 & 2006. The Allegro BAY had a 34 & 37 foot models I believe..just click on each model and then check the corresponding Spec page to check sizes.
I hope this has helped..and again...Welcome to iRV2!!