How hard is it to change the transmission on a 2005 Suzuki Reno?
If you have to ask, it is very likely beyond your skill level. Find a good shop to do it. Good Luck.
I just googled the car, and it appears to be a subcompact front wheel drive car with a transverse engine
That means you’ll need to support the engine from above, with one of these
Then you remove the subframe . . . which is usually quite a bit of work . . . and then you can start removing the transmission, after you pop off the cv halfshafts
… especially if there is as much rust as is frequently found on a 16 year old vehicle.
Does this car have a subframe? Not all models do. If not, it should be possible to remove the engine and transmission together out the top using a shop crane. Then, lower them onto the ground (put down a piece of plywood or a plastic A/C equipment pad), unbolt the flex plate from the crankshaft, then unbolt the bell housing from the engine block.