How do I find out if I need a shroud for the projector I choose?

First thing you can do is to measure. You'll need to find out the difference between the projector (of your choice) and the hole in the reflector it's going in to or the original projector. Websites that sell projectors and shrouds have the measurements posted. If measuring is not an option, you can research if somebody has done it in the past, and see if they used one or if you can find the measurements. Last option is we can do the measuring and recommend the options to our customers.