I've a 4-236 with a paragon tranny, don't remember the model. The dipstick is near the breather cap, which itself looks like it could be a dipstick. Both are under a plate near the aft port side that hides them pretty well, and takes some good dexterity to extract the stick.
So far, I've only been able to find the dipstick hole, so I use a syringe I got from a hardware store (for dispensing glue) to fill it through the dipstick hole.
This is from our club site and may be of help for you:
Most Banjers mount Paragon 25L with Perkins 4236 and Paragon 35L with Perkins 6354. Reductions 3:1 both cases.
We thought Paragon Transmissions were not anymore in production, but Doug Frank, General Manager of Great Lakes Powers , the Original Equipment Manufacturer for the Paragon Marine Transmission, formerly The Paragon Gear Works of Tauton, Massachusetts, tells us: "We still continue to manufacture product for the Paragon units. We can still provide a complete unit depending on the model. We can provide for most units complete seal and gasket kits as well as clutch plates, bearings, brake bands, etc."
Their Paragon web site is at: Paragon Marine Hydraulic Transmissions