Ratting sound on 1st gear
 

Never heard of a Camdam before...Start with simple basic stuff ,as in don't overlook things that could cause noise you think is coming from transmission.1St and 2nd on list is transmmision mount and engine mounts. Trans mounts on 1st gens are known to separate and allow trans to move around particularly when starting off in 1st gear.Same for engine mounts. These need to be looked at closely to verify the rubber in mount has not separated from metal bracket that retains it. More than likely with the age/miles on your car the trans mount is separated or in the process.

Check for loose/rusted heat shields on your exhaust system and on underside of car. These can make all kinds of weird noises. Check exhaust system hangers,with age they can sag or split allowing exhaust system to hang lower and come into contact with something to generate noise.

For the most part,1st gen manual transmissions are pretty simple and sturdy for a light duty unit. A lot of times noises aren't coming from inside the actual transmission. There have been members here that have had transmissions rebuilt,(and the shop rebuilt a good transmission)Charged them only to have the same noise and to later find out the noise wasn't in the transmission at all but coming from accessories on the engine.

Don't assume,it gets expensive and if a shop is telling you something,you can always take to another shop for 2nd opinion-just like a doctor.

Do you have a chrome dial-type fuel pressure regulator? Like this.

Mine rattles at higher rpm, sounds like it's coming from the transmission sometimes.