BobB Posted March 6, 2016 Report Share Posted March 6, 2016 I've read and learned a lot from the various threads, but have a few direct questions needing expert opinions: I have a 52 B3B with a 218. 1) Is there a sure way to tell the specs on my rear gears without opening it up? It tops out about 45 mph. Can I trust that it's a 4.11, 8.75 inch with 10 splines? 2) If not, can I find out everything I need to know just by removing the cover? I have a leak, so I have some investigating anyway. 3) Is diameter, ratio and number of splines all the info I need to find a replacement ring and pinion that will work? Do I also need to know the shaft length and is that something I can find without removing the pinion gear? 4) Does anybody have a listing or reference that would help me identify what model of vehicle would be interchangeable but have a lower gear ratio in the 3.73 to 3.9 range (or could I go lower if I upgraded to a 230 with a bit more power?) 5) Is there a vendor that has been proven a helpful source for this type of modification? Thanks much - - Bob Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 7, 2016 Report Share Posted March 7, 2016 (edited) first off there is no cover..the hoghead has to be removed after backing out the axles...you can usually see the ratio stamped near the fill plug or on the very top of the hoghead there is a machined boss that often has the ratio there or at minimum the teeth count of the gears whereby you just do the simple math... I best ad a statement here...IF your axle has been changed in the past...though not mentioned here...you could have a cover.. Edited March 7, 2016 by Plymouthy Adams Quote Link to comment Share on other sites More sharing options...
Young Ed Posted March 7, 2016 Report Share Posted March 7, 2016 Also you need to verify with a tach your RPM at 45. You may have more left than you think. Quote Link to comment Share on other sites More sharing options...
Brent B3B Posted March 7, 2016 Report Share Posted March 7, 2016 (edited) You could also mark the tires and propeller shaft and count the revolutions as mentioned in the shop manual ( page 9) to help determine the ratio http://dodgepilothouseclub.org/know/B4_manual/B4_Axle_rear.pdf Edited March 7, 2016 by Brent B3B Quote Link to comment Share on other sites More sharing options...
Solution Phil363 Posted March 7, 2016 Solution Report Share Posted March 7, 2016 (edited) Bob, I found the fastest way to find the gear ratio is to check the external markings on the differential itself that Plymouthy Adams mentioned above. I attached my differential photo showing 4.1F that is stamped on a raised area next to the fill plug. Once I removed the axles and pulled the differential I found the 4.1 gear ratios also stamped on the main gear inside. The second photo is the 3.73 Differential with markings in the same area on the pumpkin. My 3.73 Diff came off of a 1949 4 Door Windsor. I also have the same vehicle model as you and I do not have a cover on my rear axle. I think that the Hollander manual shows which differentials interchange between our trucks and late MOPAR car models (Dodge, Plymouth, Chrysler) from the late 40's to early 50's. Phil Edited March 7, 2016 by Phil363 1 Quote Link to comment Share on other sites More sharing options...
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