original gears in a 78 400 doba

[Night Runner]

My parts car is a 78 400 BB doba and I cant seem to to find a tag on the rear axle with the gear ratio. I was wondering if anyone here would know. I am doind a 06 hemi swap in the 79 that I jsut had painted and will probably need to replace my 276 gears and thought that the other car may have a good set in it, just dont know what size they are.

Thanks in advance

 

[daredevil]

I could be wrong but I think you can jack one rear wheel up and in nuetral mark the driveshaft. /then turn the wheel and watch the drive shaft. 2 and 3/4 wheel revolutions to 1 of the driveshaft would be 2.76 and 3 and a 1/4 would be 3.23 and so on

 

[MAGNUM GT XS22L9R]

Look for your broadcast sheet, look under the back seat. If not there, look under the
front seats, carpet, under the dash or maybe in the headliner. It will have extra codes
that the data plate/fender tag does not carry. Here are some of the codes to look for.

D51 - 2.71/2.76 Axle Ratio

D52 - 2.93/2.94 Axle Ratio

D53 - 3.21/3.23 Axle Ratio

D55 - 2.45/2.47 Axle Ratio

D56 - 3.54/3.55 Axle Ratio - Zone/S.O. Only

D69 - Special Order Rear Axle

D82 - 8.25 Rear Axle Size

D85 - 9.25 Rear Axle Size / Standard Duty Non-Sure Grip

D91 - 9.25 Rear Axle Size / Heavy Duty with Sure Grip

 

[egrand1508]

Check the fender tag. If the lower left code is E64 then it almost certainly came with 2.45 gears. If the code is E68 (trailer towing package) then the gears definately were 3.23. Sure-grip was available in all ratios. If the tag is missing, then it means the rear end has been opened up before and anything could be in there. Follow daredevil's advice to know for sure.

A word of warning, the carrier for the 2.45 gears is different from others and you can't just swap gears in them.

 

[Night Runner]

Thanks for the help guys, I will check next weekend when I am at my shop.

 

[Dobaroy]

Nightrunner, most of the ones we have taken apart here have 2.4's in them with a small carrier. You would have to get a bigger carrier and 3.2 or 3.55's. It goes together pretty slick.