They are factory. It uses an Isuzu engine. I have one but it needs work. When it was running properly I got 50 miles per gallon. Non turbo so doesn't do hills very well.

I had a 82 Isuzu pup 2.2 diesel got 45 mpg cool little thing

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When replacing glow plugs do I have to replace the controller also? I understand it is expensive, and I just don't have the money. What is the worst that will happen?

As long as the existing controller works you can continue to use it.

Not that expensive though.
$85-$120 for controller
$10 for sensor
$8 ea. for bosch duratherm glows

all at rock auto

I have a 1984 chevette diesel and another engine, might consider selling if the price was right.

Loved them Chevettes back in the day never have seen a Diesel Chevette though I know they made them just never had the opportunity,Be kind of cool to see some pics of one.

I will try to get some pics of mine but it is in a different town, so will try soon.