We use reverse and drive,if I catch any of my guys wasting one minute of my time worrying if they are in drive or first they are history.We used to change alot of transmissions but we make sure they have coolers on them and we haven't changed a transmission in years.So go plow snow use a forward gear and a reverse gear,funny thing about drive gear they start in 1st gear.
Ok, i am the first one to admitt, that if you don't properly maintain a Ford Trans it will die on you. However i have never had a trans die for me, do to the fact that my plow trucks get better trans maintmance that required.
This is what i do every year, for every plow truck. (if i had a chevy or a dodge i would do the same thing) I don't do this for my class 6/7 trucks.
Fall: drain the trans completly, and install new filter.
Spring: Drain trans completly, and install new filter.
We trade our trucks every 5 to 6 years, often trade in millage is about 120 to 150 K.
Oh ya we plow in Drive and Reverse. If you read the manual that came with your truck, i am almost positive it says to plow in drive.
Let me ask you this, what how do you think your trans feels, plowing in 1st gear at 15 MPH or a long run?
Another way to save your trans, is to make sure you wait for the everything to stop spinning before you shift from drive to reverse.
Well, I plow in low. 4wd low. I then use D and R. Using low, I end up plowing in 2nd gear most of the time. The shift from 1st to 2nd is almost instant. When I plowed in 4 HI, the truck would just be shifting from 1st to 2nd as I hit the pile at the end of my run. That can't be good for the trans, hitting the pile in the midst of a shift every time. In low, I've found at the end of a push, I push the pile back farther than I did in HI. It's easier for the truck to plow in 4 low. When I do larger lots, at a faster speed, then I use HI, but it's not that often I do. My mechanic recommends plowing in low too. He's never steered me wrong since HS. He's had his share of trucks and plowing too.
My trans was adjusted, or built for plowing and towing. I had it done after the blizard of 96 here. The trans guy caught on, after having a month's worth of 16 hr days of work, and a lot full of plow trucks that just kept coming and coming and coming. He was backed up bad. He changed all the shift points in the transmissions he put in. My truck holds second gear up to 45 mph when towing a loaded trailer. It shifts at 35 mph with no load, sometimes sooner. I don't know exactly what he did, but it involved a B&M shift improver kit too.
Then again, my truck is a work horse. Chevy 350 motor, TH 350 trans, NP 205 cast iron gear driven transfer case, and 14 bolt GM rear axle with 4.11:1 gear ratio. The 14 bolt is stronger than the Dana 60, if the size of the ring gear is most important. The Dana 60 has a 10 1/4" ring gear, and the GM 14 bolt has a 10 1/2" ring gear.
There is an article I wrote on using an automatic transmission for plowing in this month's issue of the Landsculptor. Those of you that are members of MDLA already have seen it. For the rest of us, we can read it online at http://www.landscape.org