Unless you have one of the plug wires disconnected.. or have swapped the engine out of something else.. the 8XX series of ford is NOT 39 eng hp
The 6xx/early 4 cyl 2000 used a 134ci gas engine.. It had about 35 engine hp, 31 belt, and 22 drawbar.
8XX/early 4 cyl 4000 use a 172ci gas engine. It had about 52 engine hp, 45 belt, and 39 drawbar.
The XX0 series were built from 55-57 and sported the same color as previous models.. IE.. red cast.. grey tin.
The XX1 series were built from 58-62 ( model years ).. and the 6X1 were refered to as workmasters.. and were all red like your paintjob. The 8X1 were called powermasters.. and had a grey tin / red cast.. but the center hood section and dash were red.. and had an eggcrate grill cover that was also red.
Diesel engines came out with the 01 series.. and you could get a 144ci for the 601 and a 172ci for the 801.
That was my point about the comment.. you have an 850 painted like a workmaster.. the 850 is quite a bit more powerfull than a workmaster with a 172ci engine vs the 134ci engine a workmaster would have.
soundguy