Pre war Marx transformer

I am not recommending a new transformer but from the looks of the cord and most probably no circuit breaker I would not use that transformer unless you want a visit from the fire department

Oh, but look on terminal side, what appears to be a UL approved label, so the transformer must still be safe to use......

@rph posted:

Is there a modern/ newer transformer to replace a pre war 13 volt Marx transformer? I am new to all of this and don't want to burn up the loco and the switches by using the wrong transformer.  Also, what size/ type transformer do I need to run a new set of K line interurban cars?

If you visit a good hobby shop that carries Lional, MTH trains they may have a low cost new/used modern transformer for purchase.  If you visit a train show almost any O gauge vendor no doubt will have good condition used modern transformer for sale under the table in the used boxes from collections they buy.  The vendor may ask what you will be running and what you plan to add on, so as to suggest the best power rated transformer for your needs.  The ubiquitous 90 watt Lionel 1033 transformer is usually a good train transformer for starters.  Look in the OGR buy/sell to see what is available.