I just want to know, is the bell housing the same internally. Be nice to know we can use a 4sp bell housing to fix a self machined 5sp.
I'd also like confirmation that the 4sp case is magnesium not aluminum. Some people say this is the case.
I made this new tread due to a customer that thinks i sold him a 4 speed to install into his mk3. The customer tells me he doesnt have a 5th gear in his mk3.
Here is one visual difference between a 4 speed mk1 transmission and a 020 5 speed tranmission. The biggest difference is the way the driver side transmission mount bolts to the transmission.
here is a 4 speed mk1 transmission you can see how there are four holes where 4 bolts bolt in from the top.
here is a 020 5 speed. You can see how the 5th gear housing has two holes at the top. Two bolts bolt up from the side. (these pictures are from a mk1 5speed fn transmission, which is very similar to mk2-mk3 020 5 speeds)
There are other differences but i believe this is the most visable difference between the two when the transmission is installed in the car.
I really dont care about your opinion
It won't fit.
There will be no provision for the rear trans mount bracket in the 4 speed casing, and there is no 5th housing to attach the support arm to.
Basically... 2 piece casing is a 4-speed, and a 3 piece casing is a 5 speed as it will have the aluminum 5th housing hanging off the end.
A quick look at the end of the trans through the drivers side of the car will tell you if it is a 4 or 5 speed as well... big round end cap (usually green with a VW logo on it) = 5speed.... flat squarish bolted-on cover = 4speed.
The 4 speed won't have a 5th detent bolt on top of the selector and you won't be able to pull the selector out of the trans, towards the rear of the car like on a 5-speed.
I do know (or strongly believe) that the 4 speed box won't have the 3 holes needed in the MK2/3 chassis to attach the rear mount bracket to, so if you DID use a 4 speed bellhousing, it could only be used to repair a MK1 5 speed as it could no longer be mounted into the MK2/3 chassis.
Some older trans cases are indeed magnesium, or they contain a lot of magnesium in the alloy. They are noticeably lighter than the aluminum cases.
I have had a couple 4 speeds in through here, and you can tell right away when you pick the empty casing up if it is aluminum or not... at least I can. After picking up nothing but aluminum cases, the magnesium case is a good bit lighter in weight and color if memory serves me.