Probably a stupid question.
The service Manual is referring to series,but what serie is a -68 442?

 

The Cutlass/442/F-85/Vista Cruiser are all A-body or A-series cars in that year.

For more info on GM car lines:

https://classicoldsmobile.com/forums...platforms.html

 

If a drawing in the manual referees to series 31 thru 48,and another one to 54 thru 86,which one is for a -68 442?

 

44

 

Thank you.

 

Ah, now I understand the question. Turn to the chart in the front section of the Chassis Service Manual that lists the various model designations. You'll see that the second and third characters of the VIN are the series designation for your model. As Allen noted, 44 is the series designation for a 1968 442. 48 would be a Vista Cruiser, 42 a Cutlass Supreme, etc. Collectively, all 31-48 series are A-body cars. Note that these model and series designations changed from year-to-year. To further complicate this, starting in the 1972 model year, Fisher Body continued to use the two digit series designators on the cowl plate but the VIN only used a single letter. And as you may have already found out, on the 1968-69 442s, many if not most had a cowl plate that showed a 36 series even though the VIN correctly showed 44. This is well documented in the factory literature.