thank you for all the helpful information looks looks like a great project. Many years ago built a motorhome on a 38' FC blue bird bus (the yellow one) replaced the 653 detroit with a 3406 cat, they all said it would not fit, but it did, ht754 Allison, ran like a bear, up hill and down. looking forward to meeting you and have you tweek my XL, all the best Steve Murphy