The 7¼” first came out in ’60 (or ’61) for a low-cost differential for the /6 A-body (only) – and was used until end of production in ‘76. Later (late '60's), it was used for 318 2-bbl A-bodies as well.
The other cars Chrysler used the 7¼” was:
- ’68-70 B-bodies /6 only (note: these will also fit FMJ’s with little effort).
- '70 E-body /6 (very few of these got made).
- ’76-89 FMJ-bodies (/6 or 318)
- Early Dakota pickups with 2.5L 4-cyl or 3.9L V6, 2*4 or 4*4 (note: the front differential ring and pinion gear set are in reverse direction (cut wise) than what rear differentials use).
Many of the pickups use 3.55 or 3.91 gear sets because of the taller tires – which does open up possibilities – but make sure you look at picture of the gear set before purchasing because the front (4*4) gear set will not work – because of the reverse cut of the gears.
I looked this up a long time ago, but Chrysler offered limited slip’s in 7¼”s for only three years (going by memory) and even then, very few selected that option.
A Limited slip was available aftermarket for a while (in the ‘80’s) – but I hadn’t seen one for sale in a long time.
Gear sets I found on eBay are: 2.2, 2.4, 2.7, 2.9, 3.2, 3.5, 3.9 and 4.1 (I left off the last digit, for it sometimes varies).
If you already have a 2.2 or a 2.4 – any of the other gear sets (except for 2.7) will wake the car up.
2.9 would be the highest I would go. 3.2 is a great combo gearset (town and highway). 3.5 would be fun for a in-town car. 4.1 might be a bit low for most people. 2.2 and 2.4 gear sets are just TOO HIGH to get any power out of a car.
When talking about differentials, a higher ratio means lower numerical number. A lower ratio is a higher numerical number.
This is an (aftermarket) ring gear and pinion for a Chrysler 7¼”.
This a ring gear/pinion set for a Chevy 7¼” front differential. Yes, I know comparing apples to oranges, but the reverse cut pattern is the same as the Dodge 7¼” front differential. The ring gear would bolt to carrier and pinion would fit into the housing – but it would be impossible to get the ring gear/carrier to fit into the housing with that pinion gear already in it.
The 7¼” can handle a mildly warmed up 318 4-bbl – without too much problem, but with that said - I’ve had to work on tons of these differentials with /6’s in them, back in the day. The entire differential (not just one part) is just not that strong.
My recommendation has been (still is) to go out and have fun but have (or be actively looking for) an 8¼” stuck under the garage work bench for it does blow. I had an 8¼” (sale pending) for this very reason, but just acquired a pair of 8¾” differentials to upgrade with (for my big blocks). I agree an 8¾” is a bit of overkill for most of us.
An 8¼” is a stout differential and is still being used in light trucks and Jeeps today.
BudW
Can't imagine one of those behind a 318.
