I believe this is a correct set.
While I have seen advertisements for the 350 engine with the Koal Kar tender pulling a 355 Hobo Rest Boxcar I have not seen one with the coach. On the other hand I have not seen any advertisements for the coaches individually whereas I have seen ads for the freight cars as separate sale items. It only makes sense that these were sold together.
The 350 lithographed engine and Koal Kar tender are adorable but pathetic, which is probably why they're rare. I suspect that they were designed as floor toys since they will hardly navigate a circle of track without derailing. (Maybe this is where the idea for "HO" [hardly operable] gauge reared its ugly head!) The wheel flanges are to poorly formed for rail service, and the clockwork motor can barely pull its own shadow!


While the 350 engine and Koal Kar tender are hard to find the yellow roof Joy Line coaches are rare, very rare. The tops of the yellow roof coaches are distinctly different from the orange and red roof coaches. The corner seams are the real telltale. If you collect Joy Line study the picture so you'll know what they are supposed to look like should you ever come across one.
I found my first yellow roof coach at York after searching for many years. I never thought I would find another but fate smiled on me again in the form of Bob's Hobby Shop where I found another.
The two are not in similar condition but I can't complain. If you have any to spare I'll gladly take them off your hands.


Here is another yellow roof passenger set. Barb Jones submitted this picture of her double coach set with the clockwork cast iron engine. The engine itself presents some question. Is the gold bell and red window trim factory correct? It makes sense as most of the competitive cast iron engines of the era had gold and red trim. But, I have never seen another Joy Line cast iron engine with the trim. What do you think?

(Courtesy of Barb Jones)