I have a 21 Force with the Detroit DD8. I did a lot of research on this in advance, but as a new engine for this application I had little but data sheets to go by. Ultimately it didn't matter as the Force and DX3 both were being shipped with Detroit DD8. I my opinion, its likely not much difference in the Detroit vs Cummins. They are similar, albeit the DD8 being around a 7% reduction in torque. Now with 10,000 miles of seat time under my belt, I would likely have done it differently, $$ considerations aside. For me the DD8 is not enough engine. That's just my opinion. Here's a link on another post here about the DD8 performance/fuel economy. As can be seen therein, each to his own. The opinions will vary, often widely.
https://www.forestriverforums.com/fo...cy-242801.html
If you can afford it, get the XL, if for nothing else the larger engine. You wont regret it.
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2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)