I have a 2003 with 146,000 miles and the rear end is leaking and the clutches are gone, after knowing about the axles and needing a rebuild anyway i decided to grab a core from a 2006 marquis.

The core is getting sent to sand blast and powder coat this weekend. I need to start ordering parts.

The only thing i planned on keeping from the donor core were the 31 spline axles and the housing,

I want to go with an eaton true track.

model #
Eaton 913A561 Detroit Truetrac 8.8" 31 Spline Differential

as far as gear choices are concerned Ive decided the gear ratio i want but on ordering the pinion spline i need advice,

I wanted to go with a set of US lightning gears and Ford 8.8" Ring and Pinion Installation Kit with Koyo ST41901 Inner Pinion Bearings but dont know if any are compatible, since I have not taken the car apart yet in case i still need to drive it for emergencies.

what other parts should I get?

the stock rear end looks in great shape and I feel confident the core and axles will hold up to the gear change and a simple tune.

after 15 years of working on turbo Mitsubishi's I picked this up last year and its just a totally different animal, I love driving the car and want to keep it as a driver for a long time, since this issue came up i am tackling it first and want to get her back on the road proper, and with the help of my neighbor a shop teacher I feel confident with quality parts the job can be done well, any help would be appreciated, I am located on the east side of Indianapolis for any fellow MM'ers.

Thanks in Advance, I look forward to having the car rebuilt over the next few years.