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No it won't, nor will the length be correct for the drive shaft. Then the leaf springs may not be spaced correctly to bolt to the S-10 axle, then the e brake cables won't match.


You have an H-190 differential... get another, and swap it in, easy 2 hour job. Pop the axles outward about 6" to disengage from the differential (4 bolts a side) remove drive shaft, 10 bolts and the differential lifts right out. Slip in the new one and put together. If you get from a PL521 or early 620 get the speedometer pinion from the transmission and swap into yours and the speedometer will stay accurate.


You have a 4.889 ratio, so look for one of the following.....



'73 620 automatic

'80 720 automatic long box



''70-'72 PL521

'73-'78 620 except '73 auto or '79 standard



'79 620 4 or 5 speed

'81-'82 720 automatic


3.90, 370, 3.545, 3.364...

720 trucks, look on bottom right of engine tag for ratio. Will say 39, 37, 35, or 33. I don't advise going below 3.70 as you don't have a strong enough engine to power it. I wouldn't go below 4.11 myself so that I could drive on the highway and into the wind.   

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Wow! I cant believe you went to such trouble to help me! It is greatly appreciated. Till now i have felt like a chump with some of the info I've been getting. You are fabulous! Thank you.

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4.11 then would work. Too low and you won't have enough power at the lower RPMs to push through the air at highway speeds, passing and climbing hills will be.... sluggish. The J13 is quite capable of very high RPMs all day, you won't hurt it even though it sounds like it's going to blow up out on the highway.

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