Classic Winnebagos & Vintage RVs

Engine does turn over but no spark to the plugs.  Where do I start chasing wires?

Fuses first,

https://www.autossquare.com/what-happens-when-you-connect-a-car-battery-backwards/

Look up starting battery backwards on google for cars.  It's the same order of operations.

Whish you luck that you didn't fry a computer.

There's no computer in a 1989, that would still be carbureted. 

Could have messed up the regulator in the alternator.

Might also mess up the ignition module.

Other things,....?

How big was the spark?

thanks for the reply.  very little spark.  a bit of a crunching noise like wading a newspaper.  The battery isolator monitor was lite up which was unusual and indicated something was wrong.  This was without the key being in the ignition.  That's when I checked the battery and found it backwards. all fuses are good.  engine cranks but only sends around 7v to the distributor.  No noticeable burnt wires.  No spark while cranking or ignition in the run position.