742B 4G32 Perrin Heater versus Red Dot Orifice Question

[Tango-Charlie]

I just purchased the Perrin Heater 6648496 and Heater Plumbing Kit 6648497 for my 742B with Mitsubishi 4G32 gas engine. The Perrin Plumbing Kit did not come with the Orifice #6585223 that goes in one of the heater lines bypass tee's. In the kit it says "not in kit". In looking at the Red Dot kit there isn't even a reference to any type of orifice. Thus my first question is why does the Perrin Plumbing Kit make mention to the orifice and it is not included in the kit and the Red Dot doesn't even have a orifice listed in the kit. The Red Dot kit was no longer available so that is why I purchased the Perrin Kit. Do I need to order the orifice for the Perrin Plumbing Kit and install it when the Red Dot plumbing kit doesn't even show any orifice? Common sense would tell me that with the water gate valve installed and when the water valve is shut off in the summer that and orifice would restrict the flow through the bypass thus possibly making the engine run too hot in the summer. Thanks in advance for the help.