Topic: 1970 9" rear axle housing yellow paint

[1970 Snake]

So I am a bit confused, as I have see several people say the yellow paint marking on the rear axle housing flange of a 1970 mustang is on the drivers side, and have seen a resent magazine article where Bob Perkins has detail a 1970 Boss 429 rear axle and he has put the yellow paint on the driver side. But when stripping the dirt and rust off my axle housing the yellow paint is definitely on the passenger side flange and area. Would like comments on this as I am going to apply the yellow paint to the passenger side as original to my car axle and want to make sure this is also correct.

[J_Speegle]

Have original examples of that yellow mark on either end of the rear end housing during 69-70 production side apparently it does not indicate direction of installation but something else. In any case document and reproduce what you find IMHO

[specialed]

we have a original car in shop now with the yellow on passenger side & seen many that way.

[bgp429]

So I am a bit confused, as I have see several people say the yellow paint marking on the rear axle housing flange of a 1970 mustang is on the drivers side, and have seen a resent magazine article where Bob Perkins has detail a 1970 Boss 429 rear axle and he has put the yellow paint on the driver side. But when stripping the dirt and rust off my axle housing the yellow paint is definitely on the passenger side flange and area. Would like comments on this as I am going to apply the yellow paint to the passenger side as original to my car axle and want to make sure this is also correct.

Do you know where you saw the article? I need to restore a B9 rear end next summer. Thanks

[J_Speegle]

Do you know where you saw the article? I need to restore a B9 rear end next summer. Thanks

Did your car not have any marks on it when you disassembled?  The subject discussed here is a prefect example of why you don't want to copy someone elses marks since they are not always/often the same. Your rear end was likely more similar to another 9" non Boss 429 built around the same time than a random Boss 429 rear end that you don't know anything about.

Plus no telling what more we may uncover or learn in the next six months

[bgp429]

Not going to randomly copy another diff. Mine has been bead blasted many years ago so all marks are gone. I think the rear end is one of the only drive train parts that might be similar to a regular production HP car.

[J_Speegle]

On transmissions (any top loader from the same period) as well as rear ends you can find and identify some basic patterns and details that seem to be repeated over and over again that IMHO are normally "safe" or reliable to reproduce once all the more important details are addressed. Things like font style, general location, some colors and inspector/assemblers markings for example.  Same workers and plants assembled these for tens of thousands of cars or more.  May be able to help as you approach these sorts of tasks

[bgp429]

Appreciate the help. Next year when I start on it will post the request.

[Armond]

I believe it indicated a 31 spline housing and what side the yellow was applied,  was determined on what end the housing was standing on. That is what I have always believed.

[J_Speegle]

Here are a couple of examples. Most of them I've seen or found appear to have been applied when the rearend was level (as installed) or on end with the paint applied to the end on the down side. But then there are examples where it appears the were applied on the top end of the housing while standing/held with the other end downward. Or could just be the results of using or or less paint on the brush when it was applied. 

[specialed]

The 69 Dearborn gt500 Shelby  we had in shop last month was exactly like jeffs last pic with the yellow runs on the rh side & it was june built.

[1970 Snake]

Lots of great comments guys thanks, Jeff, I will proceed with yellow painting the passenger side as planned. I can't really tell the extent of the yellow paint as the original housing was quit rusty, so think I should paint with the housing standing on that end and do some of the flange and about 1.5" of the housing tube, much like Bob did on the Boss 429 housing.

[J_Speegle]

Lots of great comments guys thanks, Jeff, I will proceed with yellow painting the passenger side as planned. I can't really tell the extent of the yellow paint as the original housing was quit rusty, so think I should paint with the housing standing on that end and do some of the flange and about 1.5" of the housing tube, much like Bob did on the Boss 429 housing.

Your call since you'll be answering any questions about the mark if asked and you'll need to provide what you found and why you choose what you did.

The tread has provided you with a number of options - but basically fairly similar to one another not familiar with the article you mentioned hopefully its a fairly recent one

[1970 Snake]

I found the article googling, its a Mustang Monthly/Mustang 360 article not sure of the date,  title was "Detailing and Restoring the Mustang 9-inch Rear Axle", its and excellent article for details on restoring a 69/70 9". Regarding my painting the PS flange yellow, you can see it on the picture I attached when I started this thread, that's my axle and its definitely yellow on the PS and is why I am going forward with that. Another question I have is if the PS has the yellow flange would the paper axle tag also go on that side under the inner U bolt or would it still be on the DS of the axle?

[J_Speegle]

I found the article googling, its a Mustang Monthly/Mustang 360 article not sure of the date,  title was "Detailing and Restoring the Mustang 9-inch Rear Axle", its and excellent article for details on restoring a 69/70 9". ..............

Consider that qall of the marks are not generic and can be specific to the car, year or plant the rearend came from (some marks were applied at the rearend plant while others at the car assembly plant) so be careful of copying details and applying them to your car

................ Another question I have is if the PS has the yellow flange would the paper axle tag also go on that side under the inner U bolt or would it still be on the DS of the axle?

Yes in most cases that pattern would not change IMHO on where another mark was applied