I just purchased a 1984 F41 sports coupe with the LG4 305. I was running the RPO codes on the Thirdgen.org RPO decoder, and when I put it the code Y06, it's definition came up as "Ring Gear, 9.50", Saginaw (S.P.O)" I am assuming this is an error, as it should read 7.50"?

 

Does your car have this:

Y06 PANEL,COWL KICK(CARPETED) CARPETED COWL KICK PNL

 

That car would most likely have come with either 2.93 or 3.23 gears.

In no event would it have had a truck 14-bolt. (which of course is what the 9.5" is)

Look at the G codes for the original gears. Of course who knows what's in it now; all the "codes" will tell you, is what it left the factory with.

If you REALLY want to know what gears are in it, you'll do what any SENSIBLE car buyer such as yourself would IMMEDIATELY do, even BEFORE posting on the Internet; and you'd be out there taking care of all the "deferred maintenance". Part of which will certainly be, change th erear end fluid. While you're doing that, make a point of LOOKING AT THE PARTS. That's VASTLY more positively certain than ANY "codes" will EVER be.

 

Yes it does have the carpeted kick panels. thanks, so the definition is wrong on the RPO decoder. Thanks!

 

Obviously I am well aware that these cars only came with the 7.5/7.625" rears or the dana 44 on some. My question was not what gear ratio it was, only clarifying a definition on the RPO decoder. The ratio is actually a 3.08 rear as that was the only option on 1984 LG4 auto car. Not to mention I don't know of ANYONE who would pull the rear diff cover off to "LOOK AT THE PARTS" when buying a car, even if the seller would let them. I know what is in the car. As for maintenance, I only bought the car on Fri after it sat for 2 years, so there is much more than just changing fluids to deal with.

 

None of them came with the Dana 44.

Now that you have the car, do the maintenance, and LOOK AT THE PARTS.