Granted the 617T is Titanium, but the dimensions are still the same for the 817 and the 617T. The only caveat is the cylinder is going to be slightly longer in the 617T by hundreths of inches due to the magnum chambering over the 817UL in .38 Special. So there may be some looseness. Overall though holsters for one should fit the other.
Thanks for the information. I was in Cabela's earlier this morning and they had a Galco Silhouette in stock for the Model 617. I bought it and tried my 817 in it and it fits like a glove. It's a nice high ride close to the body with an FBI cant...perfect.