gearing question

[classic67]

good evening fellow members. I have a question about gearing choise. Im sure its been covered ten times over but i couldnt find any info threw search. i have a 67 long bed it had a 352 3spd from the factory with a dana 44 rearend. it now has a 390 with a 4spd. Im trying to not kill the engine again running high rpm. Im not sure the gear size it has or the size i need to run but i have to change something. all the speed limits are so high around here i cant do any back roads its geared so low. it has 32 in tires on the rear if that helps.

[cstoyer]

If your using the NP435 you could drop your engine RPM to 2102 at 65 MPH with 3.08 gears for the 44 and your 32 inch tires. That's the highest ration I could find for the Dana 44 but it depends on how much your willing to give up on the power side. The next highest 3:31 ratio will take you to 2259 RPM.

CStoyer

[classic67]

Well i dont use it for teuck stuff anymore. Got a new truck for that. This is just my cruise to iceceeam and drop jaws on import kids. Id like a good balance running 65 would be nice right now its geared to pull a tractor home from the feild.

[eggman918]

The 390 reaches max torque at ~2,400 RPM if it were me I would want to be at or just below that at highway speed so I'm thinking 3.31's would be ideal
turning 2,259 would give you reasonable acceleration still in direct, I have been told by people whos opinion I trust that thr 390 does noe respond too well mileage wise when lugged too low......

[classic67]

Thank you for the response guys. Now just to find gears since lmc quit selling them.

[eggman918]

https://www.summitracing.com/?ibanner=HP60NavSRE1

[classic67]

I found some on there but it didnt saybif it would work on my axle. I guess there are some differences between the ford dana 44 and the jeep 44?? Maybe splines. Im not good with rearends im mostly an engine guy so this is new to me.

[eggman918]

If all you are doing is changing ratios it will be just the ring and pinion you will still be using your existing carrier so a Dana 44 is a Dana 44 as long as it's a standard rotation set, but you will need a bearing,shim and seal kit. Also doing the setup requires special tools and skills or a shop to do it correctly.