Tucker, formerly named Diesel 199 (D199), Nicknamed "Spamcan" And "Old Reliable", is a diesel who works on the Main Line.
In 1967, he along with Bear (then named D7101) first arrived on Sodor. He soon made himself an enemy of the steam engines when he claimed that "steam engines spoil our image". However, he ironically failed with a train of oil-tankers at a signal box, blocking the crossing. Henry, whose regulator had already jammed, came to help. However, after D7101's ejector leaked, making him unable to pull his passenger train, Henry was asked to help him as well. Henry, with some help from 7101, was still able to move and bravely pulled 199, the oil-tankers and the passengers to the next station. Donald and Flying Scotsman were at the station to take thier trains. Donald took the tankers while Flying Scotsman, to the delight of the passengers, took the passenger train. The Fat Controller was not impressed, and Diesel 199 was soon sent home in disgrace while Diesel 7101 was given a second chance and was bought by the North Western Railway and renamed Bear.
Decades later in 2007, D199 was given a second chance on Sodor. Although he had changed his views on steam engines, the other engines didn't trust him. When he was given a job of hauling the Flying Kipper from Brendam Docks where he met Salty. Soon, he came to Wellsworth. He slipped on the oily railway (it was an ice and fish oils dripped out and covered the van's wheels in the tracks). Spamcan's Driver and the station crew soon worked hard. But it was a long time before Spamcan was finally able to set off again. Then he continued to make his journey to Vicarstown and was on his way back to Knapford with another goods train.
Donald and Douglas felt guilty for calling him a nickname, D199 decided to name himself, but he was not sure. He and the twins toss their ideas until he got a new name better than a nickname, which was Tucker.
As Tuckers arrives at Wellsworth, pulling the express while Gordon's fire get burned, Edward asks him if he may need help, but Tuckers denies this and leaves. When Tucker comes to the hill, he picks up speed as he tries to pull the train over the hill by himself like before. But halfway up, despite his best efforts, his heavy coach pulled him back down to Wellsworth. Edward sees everything and decides to help Tucker up the hill. Then, thanks to Gordon's pushing from behind, Tucker makes it to the top and headed for Maron.
The engines became very fond of Tucker, except James, who although doesn't dislike him, doesn't like how loud and oily he is. 1 day James shouts at Tucker for getting to close to his red paint but Henry told Tucker to ignore James and comforts Tucker by telling him that he also had flaws when he was first built.
Later that same day after Tucker had brought some trucks and is waiting for James to pass by with his Slip Coaches at Wellsworth before going home. He meets Edward and Sir Topham Hatt who explains that James will pull a nonstop coaches from Knapford to Vicarstown. When James rushes by, Edward realizes that James is missing his 2 coaches Rose and Harry. Tucker thinks that he may have forgotten 1 but Sir Topham Hatt explains sternly by saying that all passenger trains must have two coaches against railway regulations. However, before he can continue Edward interrupts and the 3 of them are shocked to see the last 2 coaches have somehow detached from James' train, luckily the guard brakes them to a stop at Wellsworth, suggesting the coupling must have broken. As Edward was busy with a stopping train, Sir Topham Hatt asks Tucker if he could quickly give them to James, Tucker agreed and is quickly coupled up and pushes the coaches. James meanwhile had stopped at Cronk, the passengers are angry at being late and James is just about to go all the way back to retrieve the coaches when Tucker bustles in pushing the last 2 slip coaches. Their brother Basil was very happy to see his siblings. The slip coaches are hitched back to James train, the passengers re-board and James quickly hurries away. That evening, James apologized to Tucker for being so rude to him and he accepts James as a new friend but is mainly happy to be part of the North Western Railway.