Soft top
 

Can I swop the fabric roof from a 987 to a986

No. Won't fit.

is there a reason for this they look identical

I'm only want to use fabric I know the frame won't fit

Look at the windows on a 987 and compare them to a 986. The shape of the windows is different so the shape of the top is also different.

Why do you want the 987 top?

Thanks Kev will have to sell the 987 hood

Because it has a glass window

If you have a 986 with a plastic window you can buy a replacement aftermarket top with a glass window to install on your existing frame or you can buy a complete used top assembly from a 2003-2004 986 and swap the complete assembly.

Question
 

I thought if you installed a glass window top on a early 986 you had to use a later different frame

Car Hood Warehouse, new top fitted with glass window for £695.

They changed in the top frame in 2003 when they made some other design updates. The top went from 3 bow to 4 bow to allow for the use of a glass window. If you want an 03/04 top with a large glass window you need to update the frame too, and on earlier models the transmission and motors. However, there are aftermarket options for the pre-03 frames that include a glass window, but the glass is smaller to allow it to work with the 3 bow frame.

Link to everything you every wanted to know about the soft top:
https://sites.google.com/site/mikefocke2/installinga%2703-%2704glasstopandframeona%2797

Some people say they have issues when putting the top into service position to access the engine after they've installed an aftermarket top with the smaller glass window on their "02 and earlier cars that originally had a plastic window, using the original bows. A lot of others have said its no big deal.