Location of the Mudcrab Merchant - Elder Scrolls: Morrowind
The Mudcrab Merchant is one of 2 merchants in the game that buys almost any item you have at full price and comes with a massive amount of gold stocked. As far as I am aware the only two merchants in the game like this are the Mudcrab Merchant and the Creeper Merchant. Creeper is easier to get to but he only has 5000G whereas the Mudcrab Merchant comes with 10,000G stocked.
You can find the Mudcrab Merchant on a small island due east of Vivec - a big tip when searching for him is don't kill any Mudcrabs until you're 100% sure they're not him. There are a couple of 'normal' Mudcrabs that spawn in this area and there is no way to tell them apart by just looking at them. If you need help locating him check out my screenshot below.
Much like with all merchants in this game the Mudcrab restocks his gold every 24hrs. If you have a couple of items you want to sell then you can rest nearby for 24hrs until he restocks his gold. A tip if you plan to do this, make sure you rest a little bit away from where the Mudcrab is, this will give you some space to fight any enemies that interrupt you while you're sleeping. Last thing you need to do is accidentally hit the Mudcrab and kill the poor guy.