Ram 2500 6.4 Hemi. 3:73 or 4:10?

Yeah 4.10 for sure in the ram since 1st and 2nd are much taller than the gears in the ford and chevy.

3.73 does pretty good in the ford and chevy but I think it might run out of steam too easy in 2nd gear with 3.73 forcing a shift to 1st when towing heavy in the ram.

ib516 wrote:
The 4.10 are better in the Ram due to the fact that the ratios in the 66RFE trans are different than the competition. If you actually look at the overall ratios, 4.10 in the Ram is closer to the 3.73 in the Ford in first through third gears. Google the transmission ratios for each, you'll see what I mean.

Bingo.

Rear axle ratio must be matched with transmission internal ratios. The 66RE has I believe a 3.2:1 1st gear, compared to near 4.0:1 for GM/Ford. In this case, the steeper the rear axle the better.

On the other hand, I chose 3.21 on my 1500 because the ZF has a super deep 4.7:1 first gear.

I hate it when magazine talk about a 3.73 vs a 4.10 vs this and that without ever considering the transmission itself.

I have a 2500 6.4 with 3.73 gears it's not bad but if I ordered another one it would be with 4.10 I tow a 29 ft hideout through upstate ny

With what you want to tow, I would get the 4.10.

I just went through this and went with 3.73 because that is what the dealers stock and I didn't want to order one. We were able to get $11K off sticker on ours and $3K more than we owed on our trade so were happy at $34K for our $48K sticker SLT.

It is rated to tow 12,500, but the payload on mine is 3,000 (actually 2,986 or something) and I think even with the 4.10 gears, I couldn't tow close to the 15,500 limit for that, as 20% of a 15,000 pound 5'er is 3,000 pounds, which would eat up my whole payload.

Our loaded trailer is right around 7,500 pounds and this truck pulls it great. We just took it through the hills of southern Indiana and it was no sweat. Our next trailer will probably still be a TT and no more than 9K-10K loaded so I think this truck will still be fine. We won't have a 5'er until retirement and will have a new truck well before then, and likely a diesel.

The 4.10 are better in the Ram due to the fact that the ratios in the 66RFE trans are different than the competition. If you actually look at the overall ratios, 4.10 in the Ram is closer to the 3.73 in the Ford in first through third gears. Google the transmission ratios for each, you'll see what I mean.

Get the lowest gears you can in a gasser since you're planning on towing heavy.

Let me tell you a Ford story. I tow 11,5K with the 6.2 and 4.30 diffy.

If I had it to do over again I would be running 3.73's. New style transmissions make the difference. I could be running a higher gear empty and then just locking out 6th for towing. In 5th with the 3.73 I would be running about the same as in 6th with the 4.30.

As far as grunt off the line. I cannot give you the first gear numbers but in the old days they would be referred to as garden tractor gears. The thing barely gets moving and it is into second.

So I don't need to grunt and I could have my cake and eat it too with the 3.73.

This just may have application with the dodge also.

4:10 Love them in my 2500!

Your close to the limit with 3:73's as your towing 12k now. So I'd say go with the 4:10's. I went with the 3:73 and have no regrets, but I dont tow heavy very often.

In California you might need the extra 1st gear grunt with that weight and the 4.10 would be a benefit. Up to speed, I prefer the 3.73 as it puts 2nd gear at about 4200rpm (peak torque) at 60~mph. I've owned 3.07 to 4.56 and the 3.73 is my preference.