Any K-line cars actually 1:48??

Yes there is. Boxes are marked as "O scale classics" For box cars look for the first three digit numbers (followed by a dash and more numbers) that will be in the 700's. (A lot of the stuff you see on e-bay is not o scale.)

I have a few of the aluminum hoppers and they appear to be 1/48.  If at the right price they are great heavy cars and look nice.  Nick

As a general rule, freight cars starting with the number 7 are scale size and those starting with the number 6 are traditional/O27 size.

The aluminum passenger cars are scale 60', 72' or 80' size. The plastic 13" cars are traditional/O27 size.

The 72' heavyweight passenger carss are scale size, but the 15", or 60' heavyweights are slightly lower than the scale ones.

Thank you.

The best source of information on K-Line rolling stock is here: Legacy K-Line. Go to the page titled Item Types and it is divided into categories, including "0 Scale Freight" and "0 Gauge Freight." The latter is, generally speaking, non-scale 027. 

Older K-Line in maroon, blue, or other colored boxes is all 027. Many of these items were made on old Marx molds. The scale size items are almost always in black or black and yellow boxes. The word "Scale" usually appears somewhere on the box of a scale size item. K6xx vs. K7xx product numbers are a reliable guide only for boxcars and reefers. The scale cabooses all have 6xx series numbers, as do the very desirable aluminum tank cars and covered hoppers, as well as the die-cast coal hoppers. 

To add to the confusion, some 027 items are actually scale size. This is the case with the closed vat cars, and very likely the two and three dome tankers. 

And for even more fun, the K761 boxcars and K762 reefers are scale size, but they are not really scale models of a specific prototype. They are generic. A lot of them are quite nicely decorated. I like them to pack up and take to toy train museum operating sessions because they are quite rugged. The stirrups are metal, part of the base. The K742 series reefers are scale models approaching Atlas in quality. 

Most of the K-Line Intermodal line is scale size, but not entirely correct. The double stacks are scale size for 40' containers, but they are lettered as 48-footers. They also typically don't have correct trucks. The Front Runners may or may not be based on a real-world prototype. Real Front Runners only had four wheels, but there may have been some kind of 2-truck spine car that the K-Line cars were modeled after. I just don't know about that one. 

In the early '90s K-Line contracted with Intermountain to have 3 rail versions of their boxcars and reefers made. The bodies are full scale, same as their two rail cars but some of the underbody detail was eliminated to allow use of 3 rail trucks amd large couplers.

They stand up to the best today though their detail is very fragile. Atlas has since acquired Intermountain's O scale line and replaced the fragile detail with more durable items.

Pete

I have an abundance of K-Line "Scale" cars because I like them.  They are not as big as MTH Premier, but are bigger than Lionel Standard O.  You can go to Legacy K-Line Trains Catalog Browser and find the "O scale" from 1999 to the end of K-Line.  After that the Lionel numbers mean nothing.  The K-Line scale does measure up on 40' boxcars at 10" for the box.  Most of the O Scale cars that I have came in a black and white box.  Prior to 1999 it seems that the cars numbered in the 7000s were scale.

Bluebeard

You may find the O Scale Freight Car Guide to be helpful.

https://ogrforum.ogaugerr.com/t...ght-car-guide?page=1

Used in conjunction with the Legacy K-Line web sight it should enable you to sort out the scale from the non-scale K-Line items.  Some of K-Line's products like the K742 refrigerator cars were real gems and remain wonderful scale models.  Others were fair attempts at O scale cars from the earlier days of the 3 rail scale movement but are not quite up to today's standards.  And a few, like their box cars, just are not scale models despite what the boxes and catalogs might say.