I have been running 4:56 gears in the car. i am going to a bigger motor now, and want to run 4:10 gears in the car. Was told that they are two different cases, and that I would have to install a spacer to run the 4:10's My question is this true? does the spacer take away from the strength? Does anyone make a 4:10 gear that will bolt in without the spacer? I do run a spool. thanks.....

Usually it's the other way around if I remember right, the big gear needs a spacer and the little gear doesn't.....but I think it depends on the brand of gear.

Mine was a factory 3 series carrier and had a spacer + 4.88s in it when I got it, I took the spacer off and put 4.10s on the same carrier.

There are 2 different carriers one for 4.56+ and one for 4.30- you cant use the 4.88 carrier with a 4.10 gear. The spacer is for using a 4.56 gear on a 4.10 carrier. John spacer

I'm pretty sure that Richmond gear 4.10 street gear and pro gear are both for a 4.56-up carrier.

I am considering the same . Strange lists a 4.10part #69-0052-1 for a 4.56 up carrier without a mention of a spacer, and a pro gear#79-0011-1 for a 4 series carrier,. Are these newer parts ,i dont recall these being available ahout a year ago.

You need spacer on the 3 series carrier to run 4.56 to 5.86 gears, reason being the pinion is smaller and ring gear must be moved over...I did hear that they made a 4.10 for the 4 series carrier,,,The ring gear is thinner..I don't recommend using the spacer, I broke the ring gear bolts a number of times in my stocker with 9" slicks, 5.13 gears..Went to 4 series carrier never broke it again..

I ran 4:88's with a spacer for years without the ring gear loosening up. Changed to 4:56 didn't need the spacer.So that would tell me you wouldn't need a spacer for 4:10"s

We use the spacers all the time with no problems.There are 2 different carriers as well as thick and thin ring gears.