https://www.bing.com/videos/search?q=how+to+detremine+the+gear+ratio+in+a+727+transmission&&view=detail&mid=68DF957DF16E85999B6068DF957DF16E85999B60&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dhow%2Bto%2Bdetremine%2Bthe%2Bgear%2Bratio%2Bin%2Ba%2B727%2Btransmission%26%26FORM%3DVDVVXX Hope this link works........found a youtube link that pretty much explains the way the gear ratio is calculated. Years ago i replace an 3 pinion for a 4 pinion planetary set that i found in a spare transmission (my thought for the change was strength) but now looking back and understanding that the planetary can be modified with a steel(for strength)so with replacing the 3 pinion for the 4 pinion with nothing else change would the gear ratio remain the same? If that makes sense.......Thanks for that response  No trans guru here but not neccessarily, if the pinion gears are the same size just spaced differently in the carrier (which is what I think they do with them) then there will be no change. Going from a 4 pinion aluminium to a 5 pinion steel never made any difference to the gear ratios and was not advertised as such. We smashed a stock O/P shaft after breaking a R and P on the Dana and upgraded both at the same time. We've had a 950ft/lb motor in front of it one time with no issues @ 3950lb. ![[Linked Image]](http://i.imgur.com/HwNJX5n.jpg) ![[Linked Image]](http://i.imgur.com/5O2t4Ss.jpg)
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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