Larry,

first of all, the lok is referred to as a Krok. Crock is the stuff that we sometimes see in the forum.
The Ce 6/8 (later) Be 6/8 was as you mentioned, primarily used for freight traffic on the Gotthard route.
Back in the days, most freight trains were composed of mixed cars and did not consist of unit trains, with a few notable exceptions. You can combine any German, Swiss, Dutch, Belgian and Italian cars to make up a freight train, as trains from all over northern Europe would arrive in Basel (Muttenz), where they would be sorted accorded to destination and would then be hauled south through the Gotthard to Chiasso, where they would be marshalled and then carried further by FS Loks.
I mentioned unit trains. One of the ones that I saw in Switzerland as a child was the Weiacher Kies Train, which was composed of brown hopper cars. Coincidentally, Maerklin just happens to have released a set of three of these cars.
Other unit trains would have been car carriers, Interfrigo cooler cars or tank cars.
Because of the wide assortment of international cars that you can combine into one Gotthard freight train and the exciting variety of colours, you can pretty much feel free to mix and match.
One thing that I did not like is the fact that Maerklin SBB freight sets always include only SBB cars and that people aren't informed of the options available to them.

My Krok is from the 26730 Set. I use most of the cars along with some FS and DB box cars to complete the consist.
I will try to post a photo for you.

Regards

Mike C

Roger,

most of the freight cars in European traffic during the period 1920-1965 were 2 axled. There were some car types that employed bogies (4 axles), but these were much less common than they are today. The nice thing (for modellers) about the classic 2 axled cars is that they were relatively short in length, meaning that a train would consist of more cars than a similar consist made up of the more modern cars with bogies.

Regards

Mike C

Mike, Roger and George:

Thanks much for your great advice on Kroks. It is greatly appeciated.

Larry

Larry,

I got these sets for my Kroks:

Marklin 4786




Marklin 48803