Want to populate my new PE diesel streamliner?

Search the forum for "passengers" or "people for passenger cars" and you'll find some threads. Most get the ones from overseas off of the bay and perform some amputations for sitting and legs shortening for standing.

A recent thread on a "grand prix" vignette had some shortened people.

They don't complain much, just glad to be useful. 

RMT has small people. (http://www.readymadetoys.com/besefi.html).  The were originally made by K-Line. 

Golden Gate has small people (http://www.goldengatedepot.com/instock.html)

Sometimes on the bay you can find O scale people.  You may have to repaint theses.

The previous BEEP People are far too large for most O-gauge passenger cars.  Since these are not yet available, it's hard to say how big they are.

I ended up using 1:64 and 1:75 sized people in my MTH and Lionel passenger cars, the ones that are 1:50 are way too large.

Many of mine are the 1:75 people, but I found some 1:64 once that looked good in the K-Line cars and used them.  I've never seen them again.