I have a 1990 D250 diesel 4x4 with the three speed automatic and a 3.07 gear ratio. I would like a lower gear ratio for pulling trailers and such. I also wouldn't mind going to a 1 ton dual tired rear axle as well. I have a 88 d350 gasser found with a four speed which I am sure has a lower ratio but I will have to check it when I get there. My question is: Is there any hangups in changing the rear axle or things that I should watch for that would make my life difficult when looking at buying this gasser one ton for the axles. The gasser in question has a 360 and is 4x4 as well. I have worked on about everything but suspension is my weak point. Any help would be appreciated.

 

You know your top speed will drop down to 60 mph, right?

The gasser will have a D60 rear. It will bolt in but it's a weaker unit.

 

Yeah I know its going to reduce my top speed but I only use it as farm truck anyway. It rarely sees the highway anyway. It sees the stock trailer much more often than the highway. With the gear ratio I have it has to work awfully hard to pull anything. Is the front differential the same situation?

 

I dont think the front rear out of a gasser will hold up long at all under the weight of the cummins

 

Hmmm... A D250 is 2 wheel drive. Is yours a 4x4? I ran a gasser rear dana 60 for a while in a pinch. It will bolt in perefctly, but it is a slightly weaker axle. There are usually people on here looking to put a 3.07 rear in for the mileage. Maybe one of those people would be willing to swap you rears? Check in the classifieds on here too, there's usually a few rears for sale.

 

I guess its a w250, its definetly a 4wd. The emblems were removed for a previous paint job and I didn't even think about it what it was. The thing is this truck I am looking at has a flatbed on it I want and I was hoping the axles would work in my truck as a bonus. If the differentials would be too weak, then what is my best option in order to lower my gear ratio? Can I get a ring and pinion in maybe a 354 ratio and install in these axles I have? But then I still need to go with a one ton axle for the flatbed. I will look in the classifieds but I will be lucky to find anyone in my area to make it worthwhile. ad removed What year axles will bolt right in without a lot of modifications and how do I identify what series the axle is such as d60,d70 or d80? I suppose the best thing would be to find a junk diesel 1 ton and use those axles if the gasser axles are too weak. By the way it is three speed auto.

 

The gasser dually will have a D60 front just like a diesel dually would, no worries there. I'm more concerned about the rear D60 since this is a working truck.

The gasser probably has 4:10's at a minimum and may have 4.56's.

Your best bet is to find a donor diesel with 3.54's for the rear. You can use a 2nd gen rear, too.

 

Thanks Dave. The gasser is not going to work out. Too rough of condition and it is 4.10 anyway. The guy who owned it said it wouldn't go over 55 anyway. It would propably work if I had OD. I am still trying to find out what axles I have for sure. I found a site that had all the numbers listed but my axles have none of the right numbers that match. I will keep my eyes open and see what I find. It propably wont be to hard to find the one ton rear axle but finding both would be awfully lucky. Where is the best place to get a ring and pinion for the front if I need?