Can you determine if a Lotus 5-speed gearbox is good without first installing it?

[BrianK 78]

I bought my car knowing that it has bad 2nd and 3rd gear synchros, BUT it came with a spare gearbox.

When I bought it, the seller said that the spare was a "good" gearbox, but when I pressed him (after buying the car), he said that he didn't really know the condition of it.  In fact, he had inherited the car, and the real previous owner is now deceased; so there's really no telling.

With that... is there some way to determine if the gearbox is good before installing it?  

While I'm asking - any tips on replacing the gearbox? Does the engine have to come all the way out of the engine bay, or can I just scoot it forward a few inches while it hangs off the engine hoist?

[gusexige 1]

I have not rebuilt a 5 speed, but have done a ford 4 speed

Not really that complex. 

Pull the cover off and look at the dogs and synchros. Each gear has little doghouse shaped 'dogs' that the peak of the roof if you will gets rounded. Each synchro has the same that mate with the shifter hub. These start getting rounded day one, but if they stop looking like doghouse roofs and start looking like igloos: dead

 

 

mainshaft bearings don't usually die. 

countershaft bearings do. 

 

Anyway, take the cover off and loo at what is going on. 

 

[mikeeech 345]

The engine has to come out to get the gearbox out unfortunately. No telescopic propensity on these.

[black eclat 53]

Drain the oil and inspect for metal "fines". Use a magnet to be sure.

[gusexige 1]

I think he is saying that he has one out of the car. 

Popping the lid and taking some pics of what can be seen close up in focus would allow some speculation on condition

 

Generally the 2nd gear synchro is the most worn[since it is used more and frequently harder]