The electric rear locker is on a lot of the trucks. My 15 f150 had it. Can easily be had on a non tremor. The running boards are by no means rock sliders. Just less drop for more clearance.
While my 2 cents. The 7.3 I have about 300 miles on now is very capable. Still testing but was cruising flatter in better weather today than my first run and managed 16 mpg (US) unladen @ 60 mph, cruise control, shift algorithm ECO, for many miles. Traveled local large grades my last truck (my 2015 F150 5.0 with 3.73.1) would downshift to 5th, the Tremor today on same grade didn't wince and stayed in 10th at 1450 rpm (55 mph stretch of road). I would bet unless your doing 6-8 horse stall trailers with sleepers or over 35 foot trailers or 5 wheels weekly you will not be wanting. The diesel getting better mpg? I wonder in 80% of driving situations with the accumulative penalty $$ for upkeep the costs are more than a 1-2 mpg advantage means plus the $8800.0 option upgrade over the 7.3 (More if financed).
SO as an example for beastmode:
F250 XLT (cost conscience)
adding FX4 and Elec locker = ~$800
Tremor package $3975 (minus the above items for comparison) = $3175
Therefore IF you compare FX4 with locker to Tremor for the $3175 American you get:
35” Off-Road Tire – LT285/75R18
• 18” Low-Gloss Black Painted Wheel
• Unique Front Springs – Ride Height Increase
• Rear Electronic Locking Differential
• Front Limited Slip Differential
• Performance Front & Rear Shock Absorb (better quality than FX4)
•
Power Driver seat (8-Way) (XLT only)
• Off-Road Running Boards – Textured Matte Finish
•
Skid Plates – Transfer Case and Fuel Tank
• Unique Front Air Dams – Approach Angle Improvement
• Water Fording Vent Tubes – Transfer Case & Axle
• Rock Crawl Mode
• Trail Control Mode
• Tremor Off-Road Decal
• Spare – Conventional Road Wheel
• LT285/75R 18E BSW Spare Tire
• Wheel lip Molding – Body-Color
I tip my hat to anyone who can purchase, install, in a spotless environment, at computer assembly tolerances, all these items for the difference of $3175 including parts and labour.