1991 na shortnose vs long nose

[carspath]

I am considering a 1991 mx5 na

I have heard that early cars had a short nose ?engine bolt? (please forgive my ignorance) which could lead to significant engine problems


-would a 1991 car have this short nose engine bolt , or the more reliable long nose bolt?
can you tell by the chassis number?

-is it possible to convert the older , less reliable type to the newer more reliable type?
if so, what would need to be done , and how much do you think this would cost?

- how common is it for the short bolt type of engine to actually manifest a problem?

-what problem does the shearing of this bolt cause ?

thank-you

[carspath]

bump

info please

[carspath]

thank-you all, much appreciated

[carspath]

please could you tell me if there is a simple reliable way to differentiate a short nose engine from a long nose engine just by looking at the engine

thank you