I am looking to find a little information about the period when the Reading and the CNJ had joint operations. What years did they use the "Reading - New Jersey Central" tag line? How integrated were they?

I have seen a logo with the Reading Lines diamond surrounded by a circle saying New Jersey Central. Any idea when this was in use? Is there somewhere I can find this logo?

Someone can correct me on this, but I think this was during the time in the later years (40's-70's) that they were both controlled by the Baltimore & Ohio. They weren't exactly the same company, however they interchanged with each other more and joint services like the Qeen of the Valley (East Penn Branch) and the Black Diamond. They also often pooled euipment and it wasn't uncommon for for CNJ locomotives and coaches to be found in coal country on Reading branches.

observations from Oak Lane station in the 60's, i would spend my free time at their and Jenk.

The timetables for NJ/NY passenger service had the double logo and listed trains of both railroads.
I have a wood cigar box marked with both logos indicating dining car service, also tickets sold at Jenkintown for NY had the double logo (have one)

The New York / Philadelphia rarely had a mix of cars, normal was each railroad used their own passenger cars, express was another issue.

Towards the end of the Reading / JC anything was possible on freight, often saw RDG and JC mixed in freight but only coming from or going to NY, oddly lot's of NY freight going up the mainline bypassing the NY short-line for some reason, nothing going up to Bethlehem had any JC.
Eire ave often had JC RS3's and FM units.

Hope this helps

In my teenage years (1960-65) along the Reading's Bethlehem Branch, it was quite common to see CNJ diesels, principally RS-3's and an occasional F-M Trainmaster, on Bethlehem-Philadelphia passenger trains. Once in a while there would be an RSD-5(?). I also recall seeing (once) a Reading Baldwin roadswitcher m.u.-ed with a CNJ baby-face Baldwin cab unit at the CNJ Bethlehem engine terminal.