A few years ago I found my smiths speedo defective, on opening it up I found it half full of oil. Completely gobsmacked I eventually traced it back to the speedo drive on the (5 speed) gearbox probably having an oil seal within & it must have perished allowing oil to travel the length of the 5.5' speedo cable & into the speedometer itself rendering it inoperable. I managed to thoroughly clean the instrument and the cable of oil and refitted it and got it working again but I knew it would happen again... I got a summer's 1000 miles out of it and then it eventually succumbed. The speedo drive on the gearbox is in a position where I either have to remove the gearbox completely and then replace the drive unit - or else remove the seats, remove the carpet and cut a big hole in the propshaft central tunnel to access the drive unit and replace it.

I didn't go either route and instead came up with a third option; leave it where it is and replace the Smiths speedometer with a modern GPS one that mimics a similar classic style. This meant cutting a bigger hole in the recently made & installed wooden dash but so be it.

The GPS speedo in, all was well, it worked perfectly & I then just tied away the old speedo cable & sealed the end in a bag. Then the 1st lockdown came and the car didn't get out at all last year.

Now I have it 18" up on stands and I am getting through a long list of things to do. One of these is to make a stopper plug to screw onto the speedo drive instead of the speedo cable end; this will stop any further leak. However I don't know whether the gearbox has the correct (1.8lts) capacity of transmission oil. To be sure, I intend to drain it and refill it. I suspect I have lost maybe 300/400mls oil over time.

So this is a long route to ask - where is the filler plug on a Fiat gearbox circa 1983? I have the Argenta / 132 haynes book but it doesn't describe where it is. They describe two versions of the 5 speed box; early and late; they show a diagram on the early one with a plug on the uppermost end but it's not clear if its the forward or rearward; I suspect rearward end I am loathe to think it may be on the top of the box - but mine is from a late model not early. I imagine it is in a similar location. So I expect I will end up cutting an access hole in the tunnel... Unless one of you guys can shed some light on my problem? Ta very much...

... Just as well there's a current lockdown... No excuses for not doing the list of jobs...