Let's show vintage racing pictures. I'll start.

[HS30-H]

10 hours ago, 240260280 said:

It is interesting on the Le Mans car that the fuel was very rich to darken the rear tail panels...

That's from the diff...

 

10 hours ago, 240260280 said:

but it also looks like a large exhaust leak is also sooting-up the rocker/dogleg/lower driver door area. 

Side-exit exhaust, not rear exit.

The car was running on Nissan ECGI electronic fuel injection, and was already tired before starting the race. In late 'endurance' race spec the Works team tended to run the engines purposely rich (to help it to last) and loose, with a driver-controlled engine oil replenishment system.

Haller and his team 'inherited' this spec from the car's Works circuit race history, but without necessarily having the full knowledge of the ECGI system or many spare parts to use with it. All things considered, with the later photos of the car in the '75 Le Mans 24hrs race having been taken after 20+ hours of racing, it is not surprising that it was exhibiting the evidence of heavy breathing from all orifices...  

[HS30-H]

21 minutes ago, HS30-H said:

Side-exit exhaust, not rear exit.

 

[240260280]

Thanks... that routing is very common in drag and circle track racing but I have not noticed it in road racing. Some weight saving and heat-rerouting advantages.

Edited January 8, 2020 by 240260280

[240260280]

Is the differential rear spray carboned-up from heat or just oil mist from the breather... 24hrs of oil from all cars doing this could make for a slick track.

I would assume they had a diff oil cooler and a fairly closed system with breather + catch can.  Perhaps it or the differential failed and they are working on it in one photo?

Edited January 8, 2020 by 240260280

[HS30-H]

2 minutes ago, 240260280 said:

Is the differential rear spray carboned-up from heat or just oil mist from the breather... 24hrs of oil from all cars would make for a slick track.

Haller and his team had serious diff troubles throughout the race in '75. That's why you see the car with its back end in the air in the pits in so many photos. It delayed them greatly.

As mentioned, the car was already well used when they got it and - reportedly - they didn't have all that much in the way of spares come with it when they acquired it.

[gnosez]

Side exhaust routing is a simple way to allow access to the rear control arms, diff, half shafts, etc., without having to remove one or two exhaust pipes. It also keeps heat away from the diff. I'm running the BSR twin rear set-up and modified it to allow removal of a section of exhaust before and after the rear control arms and diff. They are sleeved and held together by springs.

[260DET]

On 1/8/2020 at 10:20 PM, HS30-H said:

Haller and his team had serious diff troubles throughout the race in '75. That's why you see the car with its back end in the air in the pits in so many photos. It delayed them greatly.

As mentioned, the car was already well used when they got it and - reportedly - they didn't have all that much in the way of spares come with it when they acquired it.

It's strange that Datsun would dump a well worn Z on them for a prominent race like Le Mans. Strange too that Haller did not ensure that the car was in good nick, I get all anal about preparing for a few hot laps.

[HS30-H]

2 hours ago, 260DET said:

It's strange that Datsun would dump a well worn Z on them for a prominent race like Le Mans.

Except that they didn't. It was nothing to do with Nissan. Haller and Schuller had got hold of an ex-Works circuit race car from South Africa (where it had been left behind by the Works team in 1973 with the intention of allowing a pair of local drivers to compete in remaining rounds of the Springbok Series, only for the series to be cancelled due to the Oil Crisis...) but it was not authorised by Nissan and they had no direct factory support. And Nissan were not happy that privateers were entering an ex-Works car at such a prestigious race. The car just wasn't suitable and, in Le Mans 24hrs terms, Hallers team was a shoestring effort.

 

2 hours ago, 260DET said:

Strange too that Haller did not ensure that the car was in good nick, I get all anal about preparing for a few hot laps.

Easy for you to say now, but this was a period where such races did have participants who were - let's face it - out of their depth. Haller and his team had an opportunity (they only just squeaked into the starting line-up through the non-participation of other qualifying cars) and they took it. They were attempting to punch above their weight, but hampered by lack of replacement/spare parts and - ultimately - full knowledge of the details of the car. This was a rather special piece of equipment, but they had not built it and they had only limited knowledge and limited spare parts. They were doing as best they could manage.

Despite their troubles, they were classified as finishers in '75. This allowed them a smooth entry to the '76 race, with the car rebuilt/refreshed, but still - inevitably - a lack of spares and running on a limited budget. It was to end in tragedy.    

[conedodger]

[conedodger]

Yikes!

[gnosez]

Start of a race at Road Atlanta with cars lined up 2 by 2 following the pace car going about 40mph. This shot is taken as cars drive under the access bridge. The uphill and sharp drop-off with the track falling away and to the right is one of the major pucker factors in the US. 

[conedodger]

Mid America Raceway in the rain...