The International Cessna^® 170 Association

The regulators, generators and alternators are available from most any aviation supply house as well as a lot of repair shops.
The diodes are very inexpensive insurance and sources and a discussion on the topic can be found here:
http://www.cessna170.org/forums/viewtop ... lit=diodes

FARRELL wrote:Due to incorrect wiring my 1953 Cessna 170B suffered an over voltage event. All avionics and the electric turn and bank were damaged or destroyed. I wonder if I need to consider rewiring my whole electrical system. I welcome any comments or advice.
Thanks Alan

What was the "incorrect wiring" event, exactly? Did you attempt to "jump start" from a 24 volt source? ...or perhaps use a 24 volt power supply to power-up your airplane?
If so...your wiring is very unlikely to be injured, despite the damage done to the avionics and T/B.....because the exact same gauge wires are also used in 24 volt systems.

Describe exactly what you mean by "incorrect wiring".

"overvoltage" is usually only an issue with alternator systems, because alternators can have failure modes which can overvolt. Generators are almost impossible to overvolt unless a mechanical failure occurs within a mechanical (vibrating points type) voltage regulator or the field suffers a mechanical failure to "ground" such as if the bearing fail or the insulators fail in the field shoes. If a field fails to "ground" the generator will continue to increase current (voltage AND amperage) until fuses blow.... so the avionics should not suffer if they are modern (which have voltage ranges from 8 to 32 or so.)
Modern avionics are more likely to be damaged by UNdervoltage.