And here you though that insect tech is hard and requires a degree in engineering(Well, it does)

This pack of 'Trons' currently consists of 4 vehicles, their advanced tier and technologies for them:

The first Spidertron you will encounter in tech progression is Pentatron:
Pentatron is low-tier spidertron, uses 5 legs to traverse the land at slow pace, armed with dual Chained Shotguns to deal with foes and is equipped with somewhat durable armor. While Pentatron has fairly small modular grid, you probably won't be able to utilize it much at this point in progression, but will compensate for it's weaknesses in later points of progression.

Second walker you may research and construct strides in - Scoutron:
The name tells it all - this is a modified Pentatron, most armor and weaponry were removed to lighten the construct. Specialized in scouting, Scoutron uses fuel very efficiently and moves at high speed. It is not defenceless though - it has. . . that thing: Inserter with a gun, and it will not fear to use it.

Our third Tron is not really far away from previous two, and is optional specialization rather than direct upgrade aswell - The Crabotron:
Now you may ask: How is Crabotron hardrer to research and construct than Penta if it has only 4 legs? Well, Crab's main focus is commiting war crimes, not just assisting engineer on the daily base building, hence the reason why it has: Much more durable armor, fairly high for it's tier damage resistances, The Heavy Flamer suited for purging and slightly bigger modular frame.

Here comes the next and currently last tier of fueled spidertrons, which is universal, and is not focused on anything - The Insectitron:
Constructed with 6 fully operational and quite agile legs, justified modular grid and armor, armed with dual Chainguns, perfect for raining lead storm upon your foes and nasty friends alike. Excellent at traversing hard terrain, stacked factory or biter nests.

Those trons do not possess fusion reactor installed and use chemical fuel to power themselves, so be sure to have some on hand.
However there is a way to install fusion reactor - Fusion powered Trons require no fuel, move faster and are equipped with bigger modular grid.

Trons are fully compatible with Spidertron remote, in fact, they require one to be remote controlled, so technological research adds a fair bit less expensive recipe for such device.